Virtual-On Force

When facing Jaguarandi I didn't have much luck trying to attack from afar. That said, I dashed in using either bumper and forward and began slashing away with a mech that was efficient in close range combat. This is primarily because his scatter shot doesn't hit you nearly as often this way, compared to long range where it's much tougher to dodge.

Personally, I'd suggest doing arcade mode after you've done some missions and have upgraded your AI, otherwise the bosses will make quick work of your partner which puts you at a severe disadvantage. If you've picked up any gems make sure to use the EX points by pressing Y at the Arcade Screen and put them in to either health or damage. These help tremendously when playing the game.