Tournament fighter RP ala Tekken (no, this doesn't explain the YYH avatar).
Doesn't even have to focus PvP: training through wacky regimens with friends, have silly contests with bitter rivals, go on journeys to fight shadow organizations lead by a talking cat, a ballet dancer, and an evil pilot who for some reason have the most ancient evil ever under their thumb, have dumb calling cards like "Tatsumaki Senpukyaku" or inaudible screaming like Mortal Kombat's Raiden, wrestle a bear that then goes home to his bear wife and his three bear kids to express his disappointment; I just feel like the setting breeds consistent creativity and interaction.