I can ́t imagine where the heck all those guys who do the mini-games in Mario party ́s etc.

But I can imagine a Mortal Kombat-style party game, where is hundreds of minigames. I have now like 142 minigame - ideas for game like that
Something like sports, puzzles, rallys and very off-topic competicions.

And every minigame have own characters to choose and everyone of them have some speciality which could help them in the competicions.

Example 1:

Mortal bowling.

Characters: Sub-zero, bo ́rai cho, Raiden, Fujin, Ermac, scorpion

In this game there are two players. Ordinary bowling except all characters can use their specialitys like scorpion can use "Spear" move and take ball back so he can throw twice or Bo ́rai cho can do earthquake after he is throwed the ball so the cones left could fall down. In the end, winner does fatality to loser, like rip his head of and does STRIKE with it.

Example 2:

Bloody - boarding

Characters: Kung Lao, Sub-zero, Raiden, Mileena, scorpion, Kitana

In a biiig mountain, 4 characters with their own theme boards and special moves and avanlanche. Characters are snowboarding to escape the avanlanche.
Winner is the last man(woman) standing. Characters can kill each other with special moves or they can be killed by avanlanche. The slope is full of boosts, barries which slow you down ( snowmans, trees etc.) and MK coins, which player have to collect 3 to use special move. If your speed is too low and you don ́t get any boosts, you ́re dead.
Kitana takes her fans and spins them for a while so the other players could be sliced. Sub-zero freeze himself so the barries won ́t effect to him. Scorpion takes his spear and with it he puls another player (if there is one of them in front of him) behind him to got boosted and the other player gets slow down. A few special powers in this game.