Violet is going to be Sprigatito, Dragonair (Though Dragonite is a good pokemon, but I like Dragonair's design more), T-tar Future form, and maybe a few others (like Gardevoir, Umbreon and even Hatterene).
Scarlet on the other hand has no plan, as I'm gonna make my family play the game with me with some twist to make it more fun for the first play through: They'll choose if the player character is male or female, the starter, nicknames and what I catch, what moves they learn/keep, if I grind or not and if I catch/kill legendaries/Mythicals or not. Basically, Twitch plays pokemon, but in real life (and knowing my family, they'll try to screw me over intentionally despite most of them knowing jack about pokemon). Should be fun.