Why Amy doesn't wear White

You've probably noticed that Amy the Gatomon only seems to want to wear colored diapers. That's because of this instance. One day, when E.D's insane little brother, C.D came over, he saw Amy. Pointing at her White diaper butt, he yelled “Naked Gato!” over and over again. This made Amy upset and she ran off crying. This made E.D spank his little brother hard. Since that day on, Amy only wears colored diapers so she won't look naked.

And what is up with C.D's diaper? Is that an earlier form of training pants?