They're not played often at all, but the game has a list of characters such as this small example:
Mario
Yoshi
Baby Waluigi
And each turn you bring one closer to the goal:
Mario
Yoshi
>Baby Waluigi
You can also use numbers or whatever the hell else you want. A couple of games have also allowed people to push characters back:
Mario
Yoshi
Baby Waluigi
When a character reaches a point per-determined by the host (for example 20 numbers/arrows/whatever), that character wins. Hope I explained it well enough.