Really Interesting Character Concept

I was thinking the other day about how cool it would be to have a champion that can copy other champions abilities. Think of a champion that all his abilities would copy either a team members or an enemies ability. But the catch is that if you use your Q to copy and ability you can only copy a Q ability with it. It would keep it balanced so you can't have 4 Ultimates copied. Any ideas or add-ons?