The green eSper allow you to make a " slide " that get you forward and consume a little bit of your sp.
The yellow one allow you to get pen sometimes when you kill a player.
The red one allow you to use a laser that will do -250hp of damage.
The orange one allow you to make a Area of effect attack that will throw them in the air, and slow down the ennemy, drain their sp and do 20hp of damage.
The blue eSper allow you to create a Shield arround your character and when you get hit it wil consume your sp and not your hp during the time your got the shield on.