Charges are unique to every robo. They are robo actions/special abilities which can help you greatly during battle.
All charges will inflict damage on the enemy. Exact damage varies from robo to robo. Most also offer a split second of invulnerability, during which the robo's surface will turn red. Charges are good combo-enders. If the enemy is hit with one, it is instantly knocked down.
There are four types of charges:
Attack
Moves straight ahead at the enemy for a direct offensive.
Evasion
Can be used before a gun round/bomb/pod hits to escape being hit. Usually characterized by flying backward.
Flak
The charge designed to combat aerial fighters. Flies quickly upward to slash at enemies.
Movement
Overcome obstacles quickly to get out of danger and launch a counter-attack.