Board Thread:General Discussion/@comment-33053086-20180313023105/@comment-4136655-20180403115813

It's never specifically stated that the Schnees can only summon Grimm. Winter if I recall just says that they can summon enemies they've defeated, never specifying if it was just Grimm, but we'll have to wait and see or wait for another CRWBY AMA.

As for Bahamut, I think Kamen Rider is referencing the Final Fantasy series, where Bahamut appears as a summon in just about every game.