If you have 4 people, definitely do Over the Falls and everyone will get the wins at the same time.
If you don't have 4, play Aqua Blast. Kill the AI, then have the remaining players stand on the same platform (preferably an edge). When that platform goes, everyone will die at the same time and everyone gets the win.
This way there's no reason to take turns, and you can finish in exactly 10 plays... which is plenty already.