Not sure if it would be even possible to implement, but it would be really neat if when you did an account search for an item that unlocks a challenger, if it would show whether you had it or not.

I -usually- buy the cash shop challengers and unlock them right away, but sometimes I forget, tell myself I'll do it later, and then surprise I'm a sad squid begging for challenger items to come back in the black friday sale so i can get that one little guy I forgot