It's an mecha found in Sparkster.
In the top view stage, when Axel Gear is seen flying, you will fall down, you and Axel Gear will appear with Giant Robots,now you have to control your mecha
L = Right punch
R = Left Punch
Y = Shot
Y (hold) = charge
Y (release) = dash
L & R = Guard
You have to shot Axel's mecha, you can still shot when you're mecha is still with the guard, however it is not recommended, since Axel mecha can destroy you arms.