i fully expect to see zubat, heracross, and absol
they've appeared in at least one of every region's dexes [since their debut]. i count hisui and sinnoh together since it's the same region. so even though absol doesn't appear in the hisui dex, it is in sinnoh's
other pokemon that meet the criteria are psyduck, magnemite, wingull, drifloon, and riolu. all of which are confirmed
there are some gen 5 - 8 pokemon that meet the criteria too but they've existed for fewer generations so i'm not sold on all of them returning yet. i do think basculin and goomy will return though. and zorua, clauncher, bounsweet, and stonjourner have already been confirmed