There was a question regarding on the possibility of House characters learning new moves.
The answer would be "no".
House characters wouldn't be able to learn new abilities on BoogaVerse (as in, roaming around and not in the Houses/Big Apple) in time as they would be turned into stone/forced to go back home.
As for house characters learning moves from other ones. While that is a sound idea, it is essentially learning new non-canonical things in their arsenal, which the rules already forbid it from the beginning. Even if they're learning from characters that exist in the same "canon" as them, it's better than simply say no to that concept.
At any rate, you'll be better off simply making an original character that can do the things you want rather than making an established character do xyz thing. Of course, this doesn't matter in Reality Vortex. Do whatever you want in that thread.
In a case of a character that can use all sorts of weapons, normally, I don't see anything wrong with it. House characters usually wield weapons or flexible. But if a character has a special item (for example, Buster Sword or Keyblade), it's exclusive to that character period. Cannot be transferred, learn or anything, unless their canon established that.
tl;dr House characters can work together, etc but can't learn moves from BoogaVerse nor from each other. It's easier, less chaotic, ease the possible arguments about Hey, this [insert character here] can't do [insert move here]! and the like.