Kanto - Kingler (It needs its redemption and hasn't been used in any major battle since the Kanto League)Question. If you could choose only 1 Pokémon from Ash's each regional team to return for the Master Class, who would be the last 7 members?
My picks would be the following.
1. Kanto- Kingler
Kingler could potentially G-Max and it hasn't had a battle since OS.
2. Johto- Bayleef
Bayleef should come back and evolve.
3. Hoenn- Glalie
It's in a similar situation to Kingler. Hasn't had a battle since the Hoenn League. Also has potential Mega Evolution.
4. Sinnoh- Gible
Obvious BDSP marketing. Also has potential Mega Evolution if it evolves all the way to Garchomp.
5. Unova- Oshawott
PLA marketing. Should at least evolve into Dewott.
6. Kalos- Greninja
How long does Squishy need him for?
7. Alola- Melmetal
Needs more screentime, has potential for G-Max.
Johto - This is a hard one, since the only one eligible imo are Totodile, Bayleef and Quilava (Due to LA promotion). But i personally would prefer Bayleef.
Hoenn - Glalie (For obvious reasons, its my favorite mon and has been done dirty in the Sinnoh League)
Sinnoh - Torterra - Redemption arc and BDSP promotion
Unova - Unfezant - Needs the redemption the most
Kalos - None of the heavy hitters (So no Hawlucha, Greninja and Talonflame), but Noivern. It needs it to show us it has grown since training with the others at the lab (Especially with Talonflame and Charizard)
Alola - Melmetal. Came way to late to make its mark.