Well I have the original Super Monkey Ball for GC, and that game is about as hardcore as they come. Seriously, only a very dedicated player will have a hope of beating it on Expert mode. If Banana Blitz is anything like the original, it's most definitely hardcore.
Edit: I just wanted to add that I generally find the whole argument of "casual" vs. "hardcore" games stupid anyway. I enjoy all kinds of games and find it to be a pretty useless distinction. Especially since it seems that everybody has a different definition of hardcore anyway.







