I am trying to find out if there are any rules for using the monster wave miniatures for mansions of madness. I know the game and its expansions only have so many monsters and their tokens, and the majority of the other minis seem to be based on Arkham horror baddies. Are their any ways of converting Arkham Horror monster stats to Mansion of Madness rules? or any stats to use for a given monster not included in Mansions or any of its expansions?

The short answer is "yes, if you give them thought." But the more interesting problem to consider is: how are those monsters going to enter play in the first place?