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XLR8 is probably the best fighter of the bunch because of his speedy attacks. You unlock him after you beat Grand Canyon.

[edit] Combos

Name	DS	PS2	PSP	Wii	Effect
Charge					XLR8 charges, damaging enemies near him.
Triple Kick					XLR8 kicks three times, moving all the while.
Drill					XLR8 drills his legs to seriously smack enemies.
Super Charge					Same as charge, except it lasts a bit longer.
Spin					XLR8 runs around in a circle really fast, damaging nearby enemies.

[edit] Specials

Can run at warpspeed =