If you control this and two Runeclaw Bears you control three creatures that among all of them don't share any single creature type.

Thrive is really hard to word if you intend it differently. You'd have to use Dead Ringers-style precision wording.

Alternatively you could either: go down to two creatures; or introduce a new wording that means "with no creature type shared any two of them"; or introduce a devotion-style term (e. g. diversity) that can be explained in less exact reminder text.

Ugh. Believe me, I know. This is probably about the sixth iteration of this mechanic I’ve tried. Until I find something better, this is the one I’ll stick with. Perhaps “... that don’t share any creature types among them.”