Conversation so far:
What is the WWF Champion?
CANNOTANSWER.
What WWF was undisputed?
to become the first wrestler to hold both championships at the same time, which made him the first-ever Undisputed WWF Champion.
what 2 championships did he have at the same time?
WWF Championship.

Question: Which other one?
Self-contained rewrite: Which other championship other than WWF