I'm thinking about getting this for my kids for Christmas. Can they share characters or not?

The information is stored on the figurine and they can be shared even over different platforms (xbox360, ps3 and 3DS). Of course since you need the figurine on the portal, only one can play with the same character at the same time.

They will both be playing on the same platform (one copy of the game/portal). So the question really is ... is anything preventing them from sharing the same character? Other than the stats being cumulative?

@TwoSe7enFive said:

They will both be playing on the same platform (one copy of the game/portal). So the question really is ... is anything preventing them from sharing the same character? Other than the stats being cumulative?

Nope, and you can even wipe the stats if you want to (but you probably will not). They can also play co-op together if they put two figurines on the portal.

cool, thanks!!!