I noticed in Pokemon Home normally when you transfer mons over that mega evolutions are automatic. I transferred over my Greninja today and saw that it has 1/2 forms to see in the Pokédex. I can’t view Ash Greninja however. It’s just speculation but I think the most loved Pokémon of 2019 may make a comeback in the dlc or sometime in the near future as Ash Greninja or Z-moves make a return sometime. If not, then Home would be cursed to never show Ash Greninja. Hoping I can explain this clearly enough. Tl;dr ash Greninja is either back or isn’t back.