Somebody challenges you to a money match where the loser has to pay the winner. Unfortunately for your opponent they didn't pick a game to money match you in. What are you money matching them in? If it was me I would pick:

Smash Bros (if they weren't a Smash player)
Fall Guys
Super Monkey Ball 2 Speedrun (unless they also speedrun this game)
Mario Kart (if they aren't a Mario Kart player)
Flappy Bird lol

What about you, what would you money match somebody in if they challenged you?