Play As Your Mii
If you press ZR+ZL together as you start playing a level (or the B button, if you're using a Wii Remote), you typically will be able to play as Nabbit. In the case of the final Star Road level, though, you'll instead be able to play as your Mii.
Play as Nabbit in Single-player
If you press ZR+ZL together as you start a level (or the B button, if you're using a Wii Remote), you'll be able to play as Nabbit in the single-player mode. Normally, he's only available when you are playing with friends.
To obtain all five file stars, you'll need to:
- Beat the last Bowser
- Find every normal and secret flag (there are 94 in all)
- Catch Nabbit when he appears in each of the first seven worlds
- Obtain every star coin in the standard 8 worlds
- Obtain all star coins in every world and level, including level 9 in Superstar Road