Yeah I’d pick Hisui too.Why not both?
Edit: Kidding aside, I’d say Hisui. Kanto Arcanine is one of Gary’s signature Pokemon.
Frankly as started before I am tired of Ash only getting five captures each series since XY and would love to see him go on a catching spree. I want him to at least have one of every type which would mean anywhere from 9 to 17 depending on how many dual types and if they want to give him something to represent each type regardless of type overlap. Though only if the multiple regional team format continues. In which case I’d be okay with seven Gen 9 Pokémon.
At most and this is only if Ash is leaving. Since we’re likely hitting a 1000 Pokémon or at least 999 if they want to save that milestone for Gen 10 I kind of want to see Ash reach 100 Pokémon which depending on how you count Ash’s Pokémon such as counting all the Tauros it literally is just 17 away, but if you exclude them. Well Ash has or had over 50 Pokémon so like somewhere between 40-50.
I know that’s a lot, but Keep in mind Goh has got over 100. While I don’t see Ash catching everything that moves I’m genuinely curious what they’d pick for him if they could cut lose even if only a little. Like there was probably a number of stuff they wanted to give him but couldn’t work them in or didn’t make the cut.