The holes let air go through the bakugan if you swallow it and choke...
It's this reason percisely. Its just like Life Savers (the candy) there's more to it than you may think, they aren't called Life Savers solely on shape (which ios probably what you thought) but the hole allows you to still breathe if it gets caught in your throat.... Theres my fact of the day for you all
I just try to put a ventus scrapper down my throat and theres like no way someone would ever choke on a bakugan, as for the lifesaver, the creator of the candy made those like that cause his daughter died choking on a piece of candy.
Rememebr that Bakugan used to be smaller, I could definately fit a B1 down my mouth (I got my tonsils out so there's much mroe room) And yes, I'm impressed, I actually forgot that part...