We tend to hew pretty close to canon on this, but I've written some stuff below.
- Cradle: My initial instinct was to answer "just regular grass stuff", but actually, it feels fitting to be weak to psychic too. Also, since it's related, my tera type is fairy.
- The pooltoy: To start with we need to figure out what type it is, given it's a hybrid. Water (buizel) + Water (vaporeon) = Water, so that's our baseline. That said, as a pooltoy, it has insulative qualities, which might imply resistance or even immunity to electric damage.
- Sparkles: Regular fairy stuff. Fae has also been trying to figure out who to complain to about being immune to dragonfire but not regular fire from a dragon. Seems like a massive oversight.
- UMBRA: I don't know.
- Taliesenn: Normal fire stuff.
So that's all the pokémon, but it's fun to consider others anyway. Emphasis is more put on finding a good typing for them, since it's fun to think through in different systems.
- Luna: I think dark is a good template here. It's thematically on point, and covers immunity to psychic attacks. Like the pooltoy, Luna's rubber should provide resistance or immunity to electric moves.
- Echo: Flying/Fairy, I think? You could also justify psychic actually. Yeah no, looking at what those shake out as, Flying/Psychic w/ levitate seems the more accurate setup.