Galar Regional Dex so far

New Pokémon, Confirmed:

1. Grookey
2. Grass Starter 2
3. Grass Start 3
4. Scorbunny
5. Fire Starter 2
6. Fire Starter 3
7. Sobble
8. Water Starter 2
9. Water Starter 3
10. Wooloo
11. Wooloo Evo 2
12. Gossifleur
13. Eldegoss
14. Dreadnaw (Gigantamax Dreadnaw)
15. Corviknight(Gigantamax Dreadnaw)
16. Yamper
17. Yamper Evo 2
18. Impidimp
19. Impidimp Evo 2
20. Alcremie (Gigantamax Alcremie)
21. Morpeko (Hangry Form Morpeko)
22. Obstagoon
23. Sirfetch'd
24. Rolycoly
25. Rolycoly evo 1
26. Cramorant
27. Polteageist
28. Duraludon pre-evo 1
29. Duraludon pre-evo 2
30. Duraludon
31. Zacian
32. Zamazenta

New Pokémon, Unconfirmed:

1. Generic rodent 1
2. Generic rodent 2
3. Generic Bug 1
4. Generic Bug 2
5. Generic Bug 3
6. Generic Bird 1
7. Generic Bird 2
8. Generic Bird 3
9. Generic Fossil I-I
10. Generic Fossil I-II
11. Generic Fossil II-I
12. Generic Fossil II-II
13. Generic Fish
14. Generic Version Counterpart I
15. Generic Version Counterpart II
16. Generic Fire I
17. Generic Fire II
18. Generic Fighting I
19. Generic Fighting II
20. Generic Ice I
21. Generic Ice II
22. Generic Psychic I
23. Generic Psychic II
24. Generic Ghost I
25. Generic Ghost II
26. Generic Genderless
27. Generic Poison I
28. Generic Poison II
29. Generic Steel I
30. Generic Steel II
31. Generic Rock I
32. Generic Rock II
33. Generic Water I
34. Generic Water II
35. Generic Pseudo I
36. Generic Pseudo II
37. Generic Pseudo III
38. Legendary III
39. Mythical I
40. Mythical II
41. Mythical III*

*Might appear for DPPt remakes, instead.

[spoiler]So far we have:

1. Minccino
2. (Cinccino)
3. (Pichu)
4. Pikachu
5. (Raichu)
6. Wishiwashi
7. Hoothoot
8. (Noctowl)
9. (Deino)
10. Zweilous
11. (Hydreigon)
12. Grubbin
13. Charjabug
14. Vikavolt
15. (Riolu)
16. Lucario
17. Trapinch
18. (Vibrava)
19. Flygon
20. (Larvitar)
21. (Pupitar)
22. Tyranitar
23. Munchlax
24. Snorlax
25. (Rufflet)
26. Braviary
27. (Espurr)
28. Meowstic
29. Wailmer
30. (Wailord)
31. Diglett
32. Dugtrio
33. Bounsweet
34. Steenee
35. (Tsareena)
36. (Rhyhorn)
37. Rhydon
38. Rhyperior
39. Hippopotas
40. (Hippowdon)
41. Snover
42. Abomasnow
43. Sawk
44. Wynaut
45. Wobbuffet
46. Stufful
47. Bewear
48. Frillish
49. (Jellicent)
50. (Golett)
51. Golurk
52. Gastly
53. Haunter
54. Gengar
55. Duskull
56. (Dusclops)
57. Dusknoir
58. Tympole
59. (Palpitoad)
60. Seismitoad
61. (Bergmite)
62. Avalugg
63. (Feebas)
64. Milotic
65. Hawlucha
66. Mantyke
67. Mantine
68. Vulpix (Regular Form)
69. Ninetales (Regular Form)
70. Wooper
71. Quagsire
72. (Charmander)
73. (Charmeleon)
74. Charizard
75. Budew
76. (Roselia)
77. (Roserade)
78. Pancham
79. Pangoro
80. Growlithe
81. Arcanine
82. Inkay
83. (Malamar)
84. Axew
85. (Fraxure)
86. (Haxorus)
87. (Onix)
88. Steelix
89. (Sneasel)
90. Weavile
91. (Cleffa)
92. (Clefairy)
93. Clefable
94. (Chinchou)
95. Lanturn
96. Bronzor
97. Bronzong
98. Combee
99. Vespiquen
100. (Caterpie)
101. Metapod
102. Butterfree
103. Eevee
104. Sylveon
105. Leafeon
106. Glaceon
107. Umbreon
108. Espeon
109. Jolteon
110. Vaporeon
111. Flareon
112. Ralts
113. (Kirlia)
114. Gallade
115. Gardevoir
116. Electrike
117. Manectric
118. Bunnelby
119. Diggersby
120. Wingull
121. (Pelipper)
122. (Joltik)
123. Galvantula
124. Machop
125. Machoke
126. Machamp
127. Goldeen
128. Seaking
129. (Lotad)
130. (Lombre)
131. Ludicolo
132. Deino
133. (Zweilous)
134. Hydreigon
135. Togepi
136. (Togetic)
137. Togekiss
138. Noibat
139. (Noivern)
140. Goomy
141. (Sliggoo)
142. Goodra
143. Mimikyu
144. Jangmo-o
145. Hakamo-o
146. Kommo-o
147. (Tyrogue)
148. (Hitmonlee)
149. (Hitmonchan)
150. Hitmontop
151. Pumpkaboo
152. (Gourgeist)
153. Maractus
154. Lapras
155. Snorunt
156. Glalie
157. Froslass
158. Mawile
159. Ferroseed
160. Ferrothorn
161. Mareanie
162. Toxapex
163. (Purrloin)
164. Liepard
165. Croagunk
166. (Toxicroak)
167. (Solosis)
168. Duosion
169. (Reuniclus)
170. (Shellos (East Sea))
171. Gastrodon (East Sea)
172. Rotom (Wash) (Normal)
173. (Axew)
174. (Fraxure)
175. Haxorus
176. (Timburr)
177. Gurdurr
178. Conkeldurr
179. (Wimpod)
180. Golisopod
181. Cottonee
182. Whimsicott
183. Qwilfish
184. Roggenrola
185. Boldore
186. Gigalith
187. (Baltoy)
188. Claydol
189. Ditto
190. Litwick
191. Lampent
192. Chandelure
193. (Bonsly)
194. Sudowoodo
195. Vanillite
196. (Vanillish)
197. Vanilluxe
198. Togedemaru
199. Swirlix
200. Slurpuff
201. Cherubi
202. (Cherrim)
203. Sigilyph
204. Pidove
205. (Tranquill)
206. (Unfezant)
207. Frillish
208. (Jellicent)
209. (Karrablast)
210. Escavalier
211. Farfetch'd
212. Sableye
213. (Honedge)
214. Doublade
215. Aegislash
216. (Cutiefly)
217. Ribombee
218. Throh
219. Morelull
220. Shiinotic
221. Phantump
222. Trevenant
223. Turtonator
224. Gothita
225. (Gothorita)
226. (Gothitelle)
227. Drampa
228. (Vullaby)
229. Mandibuzz
230. Meowth
231. (Persian)
232. Oddish
233. Gloom
234. Vileplume
235. (Bellossom)
236. (Natu)
237. Xatu
238. Munna
239. (Musharna)
240. Seedot
241. (Nuzleaf)
242. (Shiftry)
243. (Helioptile)
244. Heliolisk
245. Shuckle
246. (Pawniard)
247. Bisharp
248. (Remoraid)
249. Octillery
250. Torkoal
251. (Skorupi)
252. Drapion
253. Scraggy
254. (Scrafty)
255. (Klink)
256. (Klang)
257. Klinklang
258. (Dewpider)
259. Araquanid

Confirmed Galarian Forms:

1. Zigzagoon
2. Linoone
3. (Koffing)
4. Weezing
5. Ponyta
6. (Rapidash)

Confirmed Mythicals:

1. Mew

Confirmed by Japanese website's image:

1. (Goomy)
   [*](Sliggoo)
   [*]Goodra
2. Eevee
   [*](Flareon)
   [*](Vaporeon)
   [*](Jolteon)
   [*](Espeon)
   [*](Umbreon)
   [*](Glaceon)
   [*](Leafeon)
   [*](Sylveon)
3. Mimikyu
4. (Ralts)
   [*](Kirlia)
   [*]Gardevoir
   [*](Gallade)
5. Trubbish
6. (Garbodor)
7. Vanillite
   [*](Vanillish)
   [*](Vanilluxe)

Pokémon in items:

1. Fletchling
2. (Fletchinder)
3. (Talonflame)
4. (Remoraid)
   [*]Octillery
5. (Diglett)
6. Dugtrio (from regional map)

There's a few that I missed but I'll put them soon.[/spoiler]

Edit(27.02.2019): Put the list under spoilers, it will grow. This is for the very first trailer.

Edit 2(28.02.2019): Unconfirmed Counterpart addendum:

[spoiler=""]

Permanent counterparts:

1. Vullaby
   [*]Mandibuzz(Gender counterparts of Rufflet-line)
2. Throh (Version counterpart to Sawk)
3. Weedle
4. Kakuna
5. Beedrill(Former version counterparts to Butterfree in Gen 5)
6. Bulbasaur
7. Ivysaur
8. Venusaur(Starter counterpart to Charizard)
9. Squirtle
10. Wartortle
11. Blastoise(Starter counterpart to Charizard)
12. Shelmet
13. Accelgor (Trade counterpart to Karrablast-line)

Version counterparts:

1. Bagon
2. Shelgon
3. Salamence (Former version counterparts of Larvitar-line in D/P).
4. Aron
5. Lairon
6. Aggron (Former version counterparts of Larvitar-line in X/Y).
7. Trubbish
8. Garbodor (Former version counterparts of Minccino-line in B2/W2).
9. Baltoy
   [*]Claydol (Version counterpart to Golurk in US/UM)
10. Sableye (Version counterpart to Mawile in R/S/OR/AS)
11. Petilil (Version counterpart to Cottonee in B/W/B2/W2)
12. Lilligant (Version counterpart to Whimsicott in B/W/B2/W2)
13. Mime Jr. (Version counterpart to Bonsly in D/P/B2/W2)
14. Mr. Mime (Version counterpart to Sudowoodo in D/P/B2/W2)
15. Bellsprout
16. Victreebel (Version counterparts to Oddish-line)
17. Weepinbell
18. Spritzee
19. Aromatisse (Version counterparts to Swirlix-line)
20. Mankey
21. Primeape (Version counterparts to Meowth-line)
22. Drampa (Version counterpart to Turtonator)

[/spoiler]

Edit(05.06.2019): Revealed Pokémon from the trailer are: Steenee, Rhydon, Hippopotas, Snover, Sawk, Wobbuffet, Bewear, Stufful, Bounsweet, Frillish, Mudsdale, Golurk, Gastly, Duskull, Seismitoad, Avalugg, Milotic, Hawlucha, Mantine, Raichu, Vulpix(in the stadium's lounge) and Charizard. Rest of the direct footage shows Budew, Wynaut, Pancham, Gigalith, Growlithe, Inkay, Axew, Snorlax, Steelix, Weavile, Quagsire, Clefable, Male Meowstic, Dugtrio and Wailmer Pail. Official website's pictures confirm Diglett, Mantyke, Pangoro, Bronzor and Lanturn. Japanese website also confirms Combee. Japanese website's image showcases Goodra, Eevee, Mimikyu, Gardevoir, Trubbish, Vanillite, and Hoothoot.

Edit(07.06.2019):Octillery is shown on a building in the direct. Butterfree was also shown, but I forgot to list it.

Edit(08.06.2019): Updated counterparts.

Edit(11.06.2019): Direct showcased Wingull. Treehouse play showcased Bunnelby, Diggersby, Wingull, Metapod, Haunter, Galvantula, Machop, Machoke, Goldeen, Ludicolo, Eevee, Arcanine, Togekiss. Official English website confirms Hydreigon, Electrike, Ralts, Vespiquen and Mew.

Edit(15.06.2019): Official Chinese website showcases Noibat in the overworld in a picture.

Edit(08.07.2019): Official website confirms Jangmo-o and reconfirms Goomy. Trailer showcases Mimikyu. Japanese trailer showcases Pumpkaboo, Hakamo-o, Maractus and Hitmontop.

Edit(12.07.2019): New Japanese trailer showcases Abomasnow, Gengar, Lapras, Glalie, Ferrothorn, Toxapex and Mawile.

Edit(07.08.2019): New trailer showcases Galarian Zigzagoon, Linoone and Weezing, and Duosion. Japanese trailer also showcases Mareanie, Croagunk and Liepard.

Edit(16.08.2019): New trailer showcases Rotom Wash, Rhyperior, East Sea Gastrodon, Kommo-o, Haxorus, Conkeldurr and Machamp. Japanese trailer also showcases Golisopod and Whimsicott. English website confirms Qwilfish.

Edit(05.09.2019): New trailer showcases Vileplume, Eeveelutions and Sudowoodo. Japanese trailer showcases Claydol, Eeveelutions, Ninetales, Manectric, Boldore, Trapinch, Ditto, Togedemaru, Normal Rotom, Bronzong, Lampent, Dusknoir, Vanilluxe, Swirlix, Cherubi. Official website showcases Seaking against Cramorant. Direct footage showcases Gurdurr, Sigilyph, Litwick, Pidove, Frillish (both forms).

Edit (18.09.2019): Japanese website showcases Escavalier, and reveals Sirfetch'd, Regional Evolution of Farfetch'd. Japanese trailer showcases Gallade.

Edit (20.09.2019): Dynamax Camera website showcases Sableye, Aegislash and Ribombee.

Edit (01.10.2019): Game Informer interview confirms Throh.

Edit (05.10.2019): Live stream showcased Morelull, Shiinotic, Phantump, Cottonee and Galarian Ponyta.

Edit (14.10.2019): Download cartridges showcase Gothita and Turtonator.

Edit (15.10.2019): Download cartridges showcase Drampa and Mandibuzz.

Edit (16.10.2019): Trailer showcases Gigantamax Meowth. Official website showcases Gloom.

Edit (24.10.2019): Commercial shows Oddish, Xatu, Munna, Gardevoir, Goodra, Seedot, Chandelure, Heliolisk, Trevenant, Pyukumuku, Charjabug, Vikavolt, Shuckle, Bisharp, Octillery, Togepi, Torkoal, Slurpuff, Tympole, Wooper, Drapion, Scraggy.

Edit (08.11.2019): TV commercial showcases Klinklang.

Edit (11.11.2019): Final PV showcases Roggenrola, Doublade, Araquanid.