Species that didn't get cross generational buffs(type change, stat boost, additional evolutionary line, signature HA, Z-move): (27.11. 2019 - Updated for SwSh)

Kanto:

1. Spearow/Fearow: No special ability, no stat changes, no additional evolutionary members, nothing. It also lacks a third Ability.
2. Venonat/Venomoth: No special ability, no stat changes, no additional evolutionary members, nothing.This line has also not reappeared in a regional dex since Johto.
3. Psyduck/Golduck: Originally had a signature Ability, Cloud Nine, but currently it hasn't seen any boosts since.
4. Mankey/Primeape: No special ability, no stat changes, no additional evolutionary members, nothing. It just recently got a major moveset boost and that was it.
5. Growlithe/Arcanine: No special ability, no stat changes, no additional evolutionary members, nothing. It used to have a signature move in Gen II.
6. Tentacool/Tentacruel: No special ability, no stat changes, no additional evolutionary members, nothing.
7. Seel/Dewgong: No special ability, no stat changes, no additional evolutionary members, nothing. This line has also not reappeared in a regional dex since Johto.
8. Shellder/Cloyster: No special ability, no stat changes, no additional evolutionary members, nothing. Shellder-line originally had Skill Link as a signature Ability, but it no longer holds it exclusively.
9. Drowzee/Hypno: No special ability, no stat changes, no additional evolutionary members, nothing.
10. Goldeen/Seaking: No special ability, no stat changes, no additional evolutionary members, nothing.
11. Staryu/Starmie: No special ability, no stat changes, no additional evolutionary members, nothing.
12. Tauros: No special ability, no stat changes, no additional evolutionary members, nothing.
13. Omanyte/Omastar: No special ability, no stat changes, no additional evolutionary members, nothing.
14. Kabuto/Kabutops: No special ability, no stat changes, no additional evolutionary members, nothing.
15. Articuno/Zapdos/Moltres: No special ability, no stat changes, no additional evolutionary members, nothing.
16. Dratini/Dragonair/Dragonite: No special ability, no stat changes, no additional evolutionary members, nothing.

Johto:

1. Chikorita/Bayleef/Meganium: No special ability, no stat changes, no additional evolutionary members, nothing.
2. Totodile/Croconaw/Feraligatr: No special ability, no stat changes, no additional evolutionary members, nothing.
3. Cyndaquil/Quilava/Typhlosion: No special ability, no stat changes, no additional evolutionary members, nothing.
4. Sentret/Furret: No special ability, no stat changes, no additional evolutionary members, nothing. Furret recently gained a nice boost to its movepool but that was it.
5. Ledyba/Ledian: No special ability, no stat changes, no additional evolutionary members, nothing.
6. Chinchou/Lanturn: No special ability, no stat changes, no additional evolutionary members, nothing.
7. Natu/Xatu: No special ability, no stat changes, no additional evolutionary members, nothing.
8. Sunkern/Sunflora: No special ability, no stat changes, no additional evolutionary members, nothing.
9. Wooper/Quagsire: No special ability, no stat changes, no additional evolutionary members, nothing.
10. Unown: No special ability, no stat changes, no additional evolutionary members, nothing.
11. Girafarig: No special ability, no stat changes, no additional evolutionary members, nothing.
12. Pineco/Forretress: No special ability, no stat changes, no additional evolutionary members, nothing. This line also has not reached its third ability.
13. Dunsparce: No special ability, no stat changes, no additional evolutionary members, nothing.  It just recently got a major moveset boost and that was it.
14. Shuckle: No special ability, no stat changes, no additional evolutionary members, nothing.
15. Teddiursa/Ursaring: No special ability, no stat changes, no additional evolutionary members, nothing.
16. Remoraid/Octillery: No special ability, no stat changes, no additional evolutionary members, nothing.
17. Delibird: No special ability, no stat changes, no additional evolutionary members, nothing. It just got Drill Peck and that was it.
18. Skarmory: No special ability, no stat changes, no additional evolutionary members, nothing.
19. Phanpy/Donphan: No special ability, no stat changes, no additional evolutionary members, nothing. It lacks its third Ability as well.
20. Stantler: No special ability, no stat changes, no additional evolutionary members, nothing.
21. Miltank: No special ability, no stat changes, no additional evolutionary members, nothing.
22. Entei/Raikou/Suicune: No special ability, no stat changes, no additional evolutionary members, nothing.
23. Lugia/Ho-oh: No special ability, no stat changes, no additional evolutionary members, nothing.
24. Celebi: No special ability, no stat changes, no additional evolutionary members, nothing.

Hoenn:

1. Poochyena/Mightyena: No special ability, no stat changes, no additional evolutionary members, nothing. It just gained a few more Level-Up moves and that was it.
2. Lotad/Lombre/Ludicolo: No special ability, no stat changes, no additional evolutionary members, nothing. It used to have Rain Dish as a signature Ability and that was it.
3. Seedot/Nuzleaf/Shiftry: No special ability, no stat changes, no additional evolutionary members, nothing.
4. Shroomish/Breloom: No special ability, no stat changes, no additional evolutionary members, nothing.
5. Nincada/Ninjask/Shedinja: No special ability, no stat changes, no additional evolutionary members, nothing.
6. Slakoth/Vigoroth/Slaking: No special ability, no stat changes, no additional evolutionary members, nothing. It used tı have Truant as a signature Ability and that was it.
7. Makuhita/Hariyama: No special ability, no stat changes, no additional evolutionary members, nothing.
8. Plusle/Minun: No special ability, no stat changes, no additional evolutionary members, nothing. They used to have Plus/Minus as a signature Ability and that was it.
9. Gulpin/Swalot: No special ability, no stat changes, no additional evolutionary members, nothing.
10. Wailmer/Wailord: No special ability, no stat changes, no additional evolutionary members, nothing.
11. Torkoal: No special ability, no stat changes, no additional evolutionary members, nothing. It recently gained a secondary ability, Drought, however.
12. Spinda: No special ability, no stat changes, no additional evolutionary members, nothing.
13. Spoink/Grumpig: No special ability, no stat changes, no additional evolutionary members, nothing.
14. Trapinch/Vibrava/Flygon: No special ability, no stat changes, no additional evolutionary members, nothing.
15. Cacnea/Cacturne: No special ability, no stat changes, no additional evolutionary members, nothing. It lacks its third Ability as well.
16. Zangoose/Seviper: No special ability, no stat changes, no additional evolutionary members, nothing. Zangoose has a signature ability, Toxic Boost, but this is not a significant ability, just a specialized version of Guts.
17. Barboach/Whiscash: No special ability, no stat changes, no additional evolutionary members, nothing.
18. Corphish/Crawdaunt: No special ability, no stat changes, no additional evolutionary members, nothing.
19. Baltoy/Claydol: No special ability, no stat changes, no additional evolutionary members, nothing.
20. Lileep/Cradily: No special ability, no stat changes, no additional evolutionary members, nothing.
21. Anorith/Armaldo: No special ability, no stat changes, no additional evolutionary members, nothing.
22. Feebas/Milotic: No special ability, no stat changes, no additional evolutionary members, nothing.
23. Tropius: No special ability, no stat changes, no additional evolutionary members, nothing.
24. Spheal-Sealeo-Walrein: No special ability, no stat changes, no additional evolutionary members, nothing.
25. Clamperl-Huntail-Gorebyss: No special ability, no stat changes, no additional evolutionary members, nothing.  It just recently got a major moveset boost and that was it.
26. Regirock/Regice/Registeel: No special ability, no stat changes, no additional evolutionary members, nothing.
27. Jirachi: No special ability, no stat changes, no additional evolutionary members, nothing.
28. Deoxys: No special ability, no stat changes, no additional evolutionary members, nothing.

Sinnoh:

1. Turtwig/Grotle/Torterra: No special ability, no stat changes, no additional evolutionary members, nothing.
2. Chimchar/Monferno/Infernape: No special ability, no stat changes, no additional evolutionary members, nothing.
3. Piplup/Prinplup/Empoleon: No special ability, no stat changes, no additional evolutionary members, nothing.
4. Bidoof/Bibarel: No special ability, no stat changes, no additional evolutionary members, nothing. Bidoof-line recently gained a nice boost to its movepool but that was it.
5. Kricketot/Kricketune: No special ability, no stat changes, no additional evolutionary members, nothing. It lacks its third Ability as well.
6. Shinx/Luxio/Luxray: No special ability, no stat changes, no additional evolutionary members, nothing.
7. Cranidos/Rampardos: No special ability, no stat changes, no additional evolutionary members, nothing.
8. Shieldon/Bastiodon: No special ability, no stat changes, no additional evolutionary members, nothing.
9. Burmy/Wormadam/Mothim: No special ability, no stat changes, no additional evolutionary members, nothing.
10. Combee/Vespiquen: No special ability, no stat changes, no additional evolutionary members, nothing.
11. Pachirisu: No special ability, no stat changes, no additional evolutionary members, nothing.
12. Shellos/Gastrodon: No special ability, no stat changes, no additional evolutionary members, nothing.
13. Cherubi/Cherrim: No special ability, no stat changes, no additional evolutionary members, nothing.
14. Drifloon/Drifblim: No special ability, no stat changes, no additional evolutionary members, nothing. Though Drifloon currently has a signature Ability, Flare Boost, it is unlikely that this will remain so.
15. Glameow/Purugly: No special ability, no stat changes, no additional evolutionary members, nothing.
16. Stunky/Skuntank: No special ability, no stat changes, no additional evolutionary members, nothing. Stunky-line recently gained a nice boost to its movepool, but that was it.
17. Bronzor/Bronzong: No special ability, no stat changes, no additional evolutionary members, nothing. Though Bronzong currently has a signature Ability, Heatproof, it is unlikely that this will remain so.
18. Chatot: No special ability, no stat changes, no additional evolutionary members, nothing. Chatot currently has a signature move, Chatter, but that's it.
19. Spiritomb: No special ability, no stat changes, no additional evolutionary members, nothing.
20. Hippopotas/Hippowdon: No special ability, no stat changes, no additional evolutionary members, nothing.
21. Skorupi/Drapion: No special ability, no stat changes, no additional evolutionary members, nothing.
22. Croagunk/Toxicroak: No special ability, no stat changes, no additional evolutionary members, nothing.
23. Carnivine: No special ability, no stat changes, no additional evolutionary members, nothing.
24. Finneon/Lumineon: No special ability, no stat changes, no additional evolutionary members, nothing.
25. Weavile: No special ability, no stat changes, no additional evolutionary members, nothing.
26. Uxie/Mesprit/Azelf: No special ability, no stat changes, no additional evolutionary members, nothing.
27. Dialga/Palkia/: No special ability, no stat changes, no additional evolutionary members, nothing.
28. Heatran: No special ability, no stat changes, no additional evolutionary members, nothing.
29. Regigigas: No special ability, no stat changes, no additional evolutionary members, nothing.
30. Cresselia: No special ability, no stat changes, no additional evolutionary members, nothing.
31. Phione: No special ability, no stat changes, no additional evolutionary members, nothing.
32. Manaphy: No special ability, no stat changes, no additional evolutionary members, nothing.
33. Darkrai: No special ability, no stat changes, no additional evolutionary members, nothing.
34. Arceus: No special ability, no stat changes, no additional evolutionary members, nothing.

Unova:

1. Victini: No special ability, no stat changes, no additional evolutionary members, nothing.
2. Snivy/Servine/Serperior: No special ability, no stat changes, no additional evolutionary members, nothing.
3. Tepig/Pignite/Emboar: No special ability, no stat changes, no additional evolutionary members, nothing.
4. Oshawott/Dewott/Samurott: No special ability, no stat changes, no additional evolutionary members, nothing.
5. Patrat/Watchog: No special ability, no stat changes, no additional evolutionary members, nothing.
6. Purrloin/Liepard: No special ability, no stat changes, no additional evolutionary members, nothing.
7. Pansage/Simisage: No special ability, no stat changes, no additional evolutionary members, nothing.  It just recently got a major moveset boost and that was it.
8. Pansear/Simisear: No special ability, no stat changes, no additional evolutionary members, nothing.  It just recently got a major moveset boost and that was it.
9. Panpour/Simipour: No special ability, no stat changes, no additional evolutionary members, nothing.  It just recently got a major moveset boost and that was it.
10. Munna/Musharna: No special ability, no stat changes, no additional evolutionary members, nothing.
11. Blitzle/Zebstrika: No special ability, no stat changes, no additional evolutionary members, nothing.
12. Drilbur/Excadrill: No special ability, no stat changes, no additional evolutionary members, nothing.
13. Timburr/Gurdurr/Conkeldurr: No special ability, no stat changes, no additional evolutionary members, nothing.
14. Throh/Sawk: No special ability, no stat changes, no additional evolutionary members, nothing.
15. Petilil/Lilligant: No special ability, no stat changes, no additional evolutionary members, nothing.
16. Basculin: No special ability, no stat changes, no additional evolutionary members, nothing.
17. Maractus: No special ability, no stat changes, no additional evolutionary members, nothing.
18. Scraggy/Scrafty: No special ability, no stat changes, no additional evolutionary members, nothing.
19. Sigilyph: No special ability, no stat changes, no additional evolutionary members, nothing.
20. Tirtouga/Carracosta: No special ability, no stat changes, no additional evolutionary members, nothing.
21. Archen/Archeops: No special ability, no stat changes, no additional evolutionary members, nothing.
22. Zorua/Zoroark: No special ability, no stat changes, no additional evolutionary members, nothing.
23. Minccino/Cinccino: No special ability, no stat changes, no additional evolutionary members, nothing.
24. Gothita/Gothorita/Gothitelle: No special ability, no stat changes, no additional evolutionary members, nothing.
25. Solosis/Duosion/Reuniclus: No special ability, no stat changes, no additional evolutionary members, nothing.
26. Ducklett/Swanna: No special ability, no stat changes, no additional evolutionary members, nothing.
27. Vanillite/Vanillish/Vanilluxe: No special ability, no stat changes, no additional evolutionary members, nothing.
28. Deerling/Sawsbuck: No special ability, no stat changes, no additional evolutionary members, nothing.
29. Emolga: No special ability, no stat changes, no additional evolutionary members, nothing.
30. Foongus/Amoonguss: No special ability, no stat changes, no additional evolutionary members, nothing.
31. Frillish/Jellicent: No special ability, no stat changes, no additional evolutionary members, nothing.
32. Alomomola: No special ability, no stat changes, no additional evolutionary members, nothing.
33. Joltik/Galvantula: No special ability, no stat changes, no additional evolutionary members, nothing.
34. Klink/Klang/Klinklang: No special ability, no stat changes, no additional evolutionary members, nothing.
35. Tynamo/Eelektrik/Eelektross: No special ability, no stat changes, no additional evolutionary members, nothing.
36. Elgyem/Beheeyem: No special ability, no stat changes, no additional evolutionary members, nothing.
37. Litwick/Lampent/Chandelure: No special ability, no stat changes, no additional evolutionary members, nothing.
38. Axew/Fraxure/Haxorus: No special ability, no stat changes, no additional evolutionary members, nothing.
39. Shelmet/Accelgor: No special ability, no stat changes, no additional evolutionary members, nothing.
40. Mienfoo/Mienshao: No special ability, no stat changes, no additional evolutionary members, nothing.
41. Golett/Golurk: No special ability, no stat changes, no additional evolutionary members, nothing.
42. Pawniard/Bisharp: No special ability, no stat changes, no additional evolutionary members, nothing.
43. Bouffalant: No special ability, no stat changes, no additional evolutionary members, nothing.
44. Rufflet/Braviary: No special ability, no stat changes, no additional evolutionary members, nothing.
45. Vullaby/Mandibuzz: No special ability, no stat changes, no additional evolutionary members, nothing.
46. Heatmor: No special ability, no stat changes, no additional evolutionary members, nothing.
47. Durant: No special ability, no stat changes, no additional evolutionary members, nothing.
48. Deino/Zweilous/Hydreigon: No special ability, no stat changes, no additional evolutionary members, nothing.
49. Larvesta/Volcarona: No special ability, no stat changes, no additional evolutionary members, nothing. It lacks its third Ability as well.
50. Cobalion/Terrakion/Virizion/Keldeo: No special ability, no stat changes, no additional evolutionary members, nothing.
51. Reshiram/Zekrom: No special ability, no stat changes, no additional evolutionary members, nothing.
52. Meloetta: No special ability, no stat changes, no additional evolutionary members, nothing.
53. Genesect: No special ability, no stat changes, no additional evolutionary members, nothing.

Kalos: All.

Edit (27.11.2019): Sword/Shield changes:

Regional forms:

1. Ponyta/Rapidash: No special ability, no stat changes, no additional evolutionary members, nothing.
2. Koffing/Weezing: No special ability, no stat changes, no additional evolutionary members, nothing.
3. Zigzagoon/Linoone: No special ability, no stat changes, no additional evolutionary members, nothing.
4. Darumaka/Darmanitan: No special ability, no stat changes, no additional evolutionary members, nothing.
5. Yamask/Cofagrigus: No special ability, no stat changes, no additional evolutionary members, nothing.

Gigantamax forms:

1. Krabby/Kingler: No special ability, no stat changes, no additional evolutionary members, nothing. This line has also not reappeared in a regional dex since Johto.
2. Lapras: No special ability, no stat changes, no additional evolutionary members, nothing.

Trubbish/Garbodor: No special ability, no stat changes, no additional evolutionary members, nothing.