The craziest Koopaling !!

[peanut butter]

I say Iggy.

 

[kat-rin koopa]

Per nearly everyone here. Lemmy's just the way he is due to having a goofball personality, Iggy revels in his insanity.

 

[Lario]

It's a tie between Iggy and Lemmy, but I voted the latter.