Mechawiggler will start the battle by moving about the wall. As it does, capture one of the two Sherms and then begin attacking Mechawiggler. Aim and shoot to cause damage to the creature. If you hit the segmented part of its body, you'll douse the lights on it. By knocking its whole body out, you'll expose the creature, allowing you to fire at will.
The next phase will begin with Mechawiggler entering a wormhole. It will try to attack you by shooting bolts of electric out of the wormhole, so make sure to dodge them as they come. Make sure to stay alert for the rays that begin to turn red, as Mechawiggler will quickly attempt to ram you after this, doing so several times. After returning to the walls, it will shoot all the more orbs at you. After knocking out the spheres one by one, Mechawiggler will extend its body and move much quicker.
When Mechawiggler stops to charge, attack as many of its body parts as you can. If you don't finish it off in one shot, it will retreat back into the wormhole and you'll be back at step one. If this happens, it will do as before and continuously try to ram you. From there, the final phase will repeat itself, giving you another opportunity to finish it off. After picking apart every bit of Mechawiggler, hit it with one more attack to end the battle.