Yeah I'm tired of the Pikahu + 5 Mons set up they've been doing since XY especially in Journeys. I was really hoping his multi-regional team would be a bit more multi-regional.
By the way was there ever a "one that got away" in Hoenn for Ash? I can't remember anyone. I mean in Kanto there was Haunter and now he has the evolved form Gengar. Sinnoh has Lucario (also Hippopotas and Snover IIRC). Johto has Larvitar and Houndour.
Unova had Venipede, Kalos had Skrelp, Alola had Wimpod and Passimian... Galar has Dreepy and Drakloak I think? There is nothing in Hoenn ringing a bell. Well now that I think about it there was that Spoink and maybe Sableye?
If Ash were to get another Kanto Pokemon seeing as the last two or three (IF you count Mr. Mime as "new") additions from Kanto were types he hadn't caught back during his Kanto run: Psychic, Dragon, and Ghost. I think I'd like a Rock or Ground type. Or Ground/Rock with Rhyhorn. He did try and catch one in the Safari Zone and I feel Rhydon could use some love. Rhydon was the very first Pokemon ever made after all.
I wouldn't want 20-30 captures though. Honestly, the maximum I feel Ash could get would be Pikachu + 17 (one Pokemon for each type). It'd be like a sports team with everyone having a spot/role (NOT doing this is what screwed over Kingler and later Palpitoad who both had the Water Starter to contend with and later Krookodile the "regional ace" for the latter). There'd be type overlap for sure, but the writers don't care about type overlap (they gave him two Fighting types for his current team for example). Just don't type overlap with the Grass, Fire, or Water Starters or whoever the regional badass is going to be without having a unique second typing.
And if they continue the multi-regional team set up in Gen 9 with nine regions there is more than enough Pokemon to go around for Ash, his companions, TRio, and his rivals to give him 17 or at least more than 5.
Yes I know 17 (18 counting Pikachu) is a lot, but that's how many types there are. Nothing I can do about it.