Regina Winberrl is really good if played well. Her Drawgun makes her an excellent alpha striker, and giving her a Shock Bazooka or a Geso Whip - if you're fortunate enough to have either, or hell, give her both if you want - ruins the target's counterattack chances; just beware of enemy Crimson Veil/Stun Regain combos. Your team will also enjoy the Auto-Regen field, especially if you have an Ion with you.
Lala Ricotte... well, she's pretty much straight support. You can give her a shield for durability or the aforementioned Geso Whip to make people back off, but you'll mostly be giving healing and dance performances to your teammates. Whether you'll use her or not depends on whether you prefer the front lines or the back lines.
Katalina B.G. is an excellent jack-of-all-trades AIR. It's easy to give her a weapon that can mop up earthbound targets, her Shock Claws let you swoop in for a melee assault without fear of reprisal, and her Boost Drain gun will keep most other AIRs grounded and you airborne. Done well the Boost Drain gun can stop the enemy from escaping since they have no boost. She also has an innate version of Accele Roll in the form of her Slide Boost, which is cool.
Destructor MAX is a beast. He comes prepackaged with all of the essential ART weapons; quickly alternating alpha strikes with the BD-Subweapon (ahue) will usually be your main method of offense, though some would argue that the railgun AMs are better replaced with something else. Probably a Jet Hammer if you have one, so you have a close range alternative.
Mach Knight Ace is a bit of a toss-up. He'd almost be one of the blank-slate multipurpose mechas if not for his LG, which will make short work of most LNDs; sans that, his effectiveness depends on how you build him. Fortunately he has all the good AIR carts - every one but Sniper Sight - and a healthy amount of capacity.
Unfortunately I don't know a whole lot about XX Cross Raptor, but I've heard good things about it. The BD weapon at least is nice, being a stun-heavy weapon that laughs in the face of enemy shields. Not sure about its parts though.
All in all I'd say the Garapon has been good to you. With some good practice on those bots, you should be able to go to town on most of the metagame-centric players.