The starters are great, but they are such a weird equal taste to me, that:
1. I can't tell which one would qualify as the "Female Pokemon" for a girl companion (but I'll get to that in the moment).
2. None of them strike me as super marketable, let's just at least leave one Pokemon unevolved, it kind of looks like they have a reason to potentially fully evolve these starters (though I agree it will depend entirely on the evolutions).
Now as for Ash we have multiple possibilities:
1. He gets all three. I'm really hoping that there is some kind of super adorable secondary like Pokemon that can act as a starter for any companion Ash has, one of the grass/fire/water Pokemon possibly or maybe something else.
2. He only get one. I feel like Ash only getting one, would be an absolute waste, because how do you choose just "one" to go to Ash. They all have their appeal, and I don't trust Game Freak (since 6th generation) to burst with lots of options here for Ash to use, probably why Ash got Two in Sun and Moon, to make up for not having a grass type at all, and Talonflame for a fire type (though that was definitely convenient for them, since Fennekin went to Serena)
3. He gets two. This I feel is the most likely, but I can't help but think it'll be a repeat. And that's because of the three I think Sobble is the least likely to go to Ash, as I said they are all neutral when it comes to appearances but Sobble seems like it would fit really well with a hypothetical female companion. Only because it has that extra added "shy cuteness" factor to it. So a repeat of 4th and 7th generation?
Because Scorbunny I feel fits Ash perfectly, it likes to run and is full of energy, I cannot imagine them completely ignoring the characteristics of Scorbunny when deciding which to give to Ash or not.
Grookey, is similar to Chimchar so I feel like it makes sense to give it to him. Plus its characteristic of boundless curiosity.
Again I'm sure most of this depends entirely on the evolutions, but I don't know, if they just stick him with one, it probably would have to be Scorbunny (because 3rd gen had Treecko and 6th gen had Froakie), but two, I expect Scorbunny and Grookey.
I can only imagine Ash with Sobble if he gets all three starters.