Which of your OCs would be salty at Mario Party, which of them would love Mario Party, and which would refuse to play Mario Party?
Had to think on this a bit! There's more than one character that could fit all three of these, so I decided to split them across different self-contained universes / stories. Also a good a reason as any to link to character pages.
Salty: Millenia is highly competitive, so you'll catch her playing just about any game - video or not - that has a win condition, and maybe a few that don't. Highly likely to get too lost in the sauce and refuse to admit that she played herself at the same time. She won't stay mad for long and isn't a poor sport about it, but she's here to win.
Love: Pam likes creating chaos, and Mario Party is great for that. She's less about winning or losing, but definitely feeds off of the highs, lows, and general frantic energy that a game like Mario Party causes in a group. Absolutely will throw a minigame if she thinks it'll be funny.
Refuse: Censa is gonna be the one who doesn't want to play, but mostly because everyone seems so upset with each other afterwards. Maybe there's something else you all could play? How about a game where everyone gets along and works towards a common goal? That'd be more fun, wouldn't it? Everyone can have a good time that way!