Shitty Pokémon design ideas:

1. A bull frog that evolves into a minotaur frog. Its base stage is a tadpole with cow tail, furry abdomen and small horns. Its second stage is a semi developed frog with sharp claws and its lower half is a semi developed cow with cow legs and a tail. Its horns are more pronounced. Its final form is a full blown anthropomorphic frog with a cow half for its legs. Its male variant has a dark coloring with sharp horns while its female variant has pastel colors with round horns. Its claws are now more closely resembling hands, while retaining their claw like structure. Its first stage is Water/Normal and in Water I group, its second stage is Water/Poison and in Water I/Field group, and its final stage is Water/Ground with Water I/Human-Like group. Its first stage is found in watery areas, its second stage is found in forests and its final stages is found in mountainous areas. Its final stage also has abilities that grant it immunity from Poison damage, alluding to its second stage.
2. A flying fox that evolves into either a vampire bat or a flying fox with werewolf characteristics. The Werebat would be gliding species with muscular design whereas the vampire bat would have overgrown leather to make it look like a cape. Both designs would lose some of their fur to look more humanoid, but both would still be fairly small. The Werebat would be Dark/Fighting, and the Vampire Bat would be Dark/Poison, whereas the base form would be Dark/Flying.
3. A flaming snake that evolves into a flaming cobra. But the catch is, the flaming part is actually its shed skin, and it uses fire to continually to shed skin, whereas its regular skin absorbs heat. The type is Fire/Poison and it gets Shed Skin/Flame Body/Flash Fire. Its shed skin is shown to eat the snake and the snake can bite its tail to roll around Ouroboros style.
4. A Rock/Psychic magnetite that gathers up more magnetic rocks to evolve, similar to Magnemite and Beldum. Each stage would get more crystals created due to aggregate psychic Power of the rocks. Its magnetic nature would also allow it get more Electric moves and Minus as an ability.
5. A baby panther that has grass fur which evolves into a panther with steppe fur which allows to camouflage itself, particularly in Grassy Terrain. Unlike conventional Grass-types this guy is blindingly fast. Its typing can be Grass/Dark, Grass/Ground or Grass/Fighting.
6. A traditional Super Rod fish with pastel colors that evolves into a Rainbow colored fish. The gimmick is that basic form would be a normal Water/Normal, while the second form would retain the type but gain Protean with insane coverage. Both forms would have average stats however.
7. An eel that uses different sea animals' shell for protection. The eel actually creates the shells to mimic the sea animals and the Pokémon based off them. It is Water/Rock and its changes its design for all its stages, finalizing in a sea urchin, starting off as a clam and having a snail shell middle stage. Each stage gives it a different move but all stages have access to Shell Smash. It swims by squirting water.
8. A literal antlion that evolves into a winged antlion. Its start would be young lion mixed with ant larva, and its middle stage would be a furball that looks like ant pupa. Its final would be a terrifying antlion with humongous wings. Its typing could be Bug/Normal, Bug/Dark or Bug/Dragon.
9. A burrowing snake with a drill tail, like Dunsparce, that evolves into armored snake due to terrestrial pressure. It stars off Ground/Poison and evolves into Steel/Poison, who uses its acid to break rocks and minerals. It might evolve by having Dig and leveling up.
10. A Dark/Normal fat mouse that looks like a squeak toy which evolves into a Dark/Fairy plush cat with max friendship. The lore explanation would be that it would have fulfilled its wish into evolving a species that won't be hunted by cat Pokémon. It would retain its mouse like characteristics like its naked tail and mouse mouth, and it would retain its omnivorous biology.
11. A garden fairy with sharp blades for hands that protects the garden from pests. Its sharp blades allow it to get high attack and large movepool, and it uses its blades to modify the plants to make them look better. Due its nature it would be immune to poisoning, but still hit super effectively by Poison type moves.
12. A Psychic-type bear that gains Ghost subtyping due to summoning and interacting with Ghosts with its Psychic powers. Its fur patterns look bizzare like Bruxish's, allowing the bear to draw away enemies.
13. A hermit crab in a transparent ice shell. It's typing can be Bug/Ice or Water/Ice.
14. A Fighting/Ice Pokémon with frozen gloves. Gloves can be frozen or made of ice.
15. A Ground/Psychic species based on a Driedel. Much like Claydol it can have Unown letters on it.
16. A Grass/Dragon reptile with cottons around it to keep itself warm.
17. A Ground/Psychic shaman with bones around it and Thick Club as a weapon.
18. A Rock/Fighting snail who is a sumo wrestler. 
19. A Fighting/Normal ferret.
20. A Rock/Steel dinosaur who is a wind-up toy with Shift Gear.
21. An Electric/Fighting species who rubs his hands constantly to generate static electricity.
22. A bug type that evolves into a Bug/Grass with a grass cocoon that evolves into a fully evolved Bug/Grass with Leaf Stone.
23. A bug type that evolves into a Bug/Fire with a burning cocoon that evolves into a fully evolved Bug/Fire with Fire Stone.
24. A Dragon/Normal-type that evolves into a different species depending on its evolutionary stone.
25. A three stage frog that evolves into a Water/Ground at final stage with Water Stone.
26. A sea urchin that evolves into a Water/Poison with Water Stone.
27. A puffer fish that evolves into a Water/Flying with Water Stone.
28. A Grass or Bug type that evolves depending on the Powder/Spore move it has. Poison Powder will cause a Poison-type, Stun Spore will cause an Electric-type, and Sleep Powder will cause a Psychic-type.
29. A side evolution that evolves into a Dark/Ghost if it has Lovely Kiss, and Fairy/Ghost if it has Sweet Kiss.
30. A side evolution that evolves into a Fairy/Psychic if has Dream Eater, and Fairy/Ghost if it has Nightmare.
31. A Ground/Grass-type that gets both Shore Up and Synthesis that is based on a desert rose.
32. A Bug-type that has two forms, one dedicated for singles and other dedicated for doubles.
33. A species that changes form after using Burn Up. While not using Burn Up, it gets Fire/Psychic. After Burn Up, it gets Ground/Ghost. 
34. A species that changes form after losing an item.
35. A species that has a different form depending on the Weather you catch it in. Sandstorm form will have Sand Stream, Regular Form will have Cloud Nine etc.
36. -Physical Eevee: A Fairy Egg Group member with the inverse gender ratio to Eevee, this little pixie starts off Normal then evolves into rest of Physical types as a replacement to Eevee. Its initial set is Rock, Fighting, Ground.
37. -Pseudo starters: A secondary group of starters, these are like Simians in that they share the same stats and BST, but unlike Simis they are based off different animals and have different stat distributions. They are all two stage, and are Fire/Normal, Grass/Normal, and Water/Normal.
38. -Fighting/Poison: A tribal fighter that uses poison darts to hunt. It eats Poison-type Pokémon to develop its own toxins and to develop antibodies against other poisons.
39. -Ghost/Fighting: A possessed punching box. Is immune to its own primary  move, Counter.
40. -Ice/Fighting: A Carpathian boar that uses snow to hide itself. Its final form is bipedal.
41. -Fire/Poison: A humanoid creature with flamethrower holes, this being lives near volcanos and picnic areas, and exhausts Poison smoke.
42. -Electric/Rock: A three-stage monster kaiju with glowing crystals all over its body. Its final form looks like a nighttime street signs.
43. A group of starters that have different final stages as different forms in the second set of games, where the secondary types are scrambled over.