I only know the Gen 1 Pokemon , but in honesty, Pikachu would probably fit Jaune... Just like his Pumpkin Pete hoodie! Cute and pathetic looking, but actually capable in a fight. Although Jaune's Pikachu shouldn't be the super-powered beast that is Ash's Pikachu, but more like an ACTUAL pikachu: Scrappy, useful, but too adorable to be taken seriously and too weak to take a heavy blow...
Of course, Jaune would be the one to fall for buying a Magicarp...
Raichu does fit Nora though; even down to the lightning bolt tail.
Ren could have Raticate or Pigeotto, both fast and hard hitting.
Pyrrha and Charizard don't have much in common, but I feel their fighting styles would compliment each other. Char being fiercely protective of her, and her incredible skill coupled with some power hits or air strikes from him whenever she leaves an opening... I just see it looking amazing!
Yang?... Well, just bear with me... Gyrados! OP AF huh? So is YANG! Her name means Yellow Dragon or something, and Gyrados IS a dragon! His colossal rage would fit nicely along hers, and if they learn to fight together, they'd be near-unstoppable.
Gen 1 didn't have the best representation of the more "exotic" pokemon types, so I can't think of anything that'd fit Weiss or Ruby, or even Blake... Maybe give Blake Meowth's evolved form, Persian, wasn't it?