Any character unlocked:
Go onto the characters click select on the first boy, then you go onto the girl
and hold down select. If you want any other character keep holding of the button
select and slide across to the next character or the character you want and take
your finger of and click select on the character you want!
Unlocking Fresh faster:
Press on the kid with the hood. While selected go over to fresh or any of the
other character and press the box where the fraction of the amount you have for
that character is. To play as say spike after fresh you'll have to do it while
selected hood kid is taken as well.
Two character tokens:
Just use your coins to buy mystery boxes, they contain character tokens and coins. Or if you run in between 2 trains than you will flip back and hit the screen and so will the cop and his dog.
This cheat is quite hard to implement, but, as well as picking up the Coin doubler multiplier, you can earn twice as many Coins if you have the Super Sneakers and Jetpack active at the same time. You should upgrade the Super Sneakers to make this easier to occur. It won't make a tremendous difference to your score, but it's nice all the same.