Start stunt mode and win the race under the pro difficulty
setting. Burn out at the start until the counter reaches about
3,000 and do not go off the track (or you will get the clean section).
Do this for about eight tracks to unlock all the characters. Note:
You will need a bike with at least all stats at about halfway
on each bar.
Trainer: +1
Trainer: +3 by Myth
Trainer: +11 by hyunicz
Trainer: +12 by hyunicz