The loss of pokemon isn't going to bother Xehanort unduly, but he doesn't like people messing with his stuff. So he will be actively working to get his critters back. Naturally, being in a big haunted castle he's going to be like a kid in a candy store, exploring and having a grand old time. A spectacle the likes of which no one has ever seen. He won't be terribly into fighting until he gets his pokemon back, being that he's rickety without them.

People he's spoken with previously, or even new CR is welcome! This is going to be fun!