Gamera blasts a fireball. MG gets rocked back on its heels, with requisite parts smoking and sparking. But then one of the little guys inside notices that that was enough heat to fuel the plasma weapon.
Gamera gets hit by the plasma grenade, but it just charges HIM back up again.
Ad nauseam...
Well, ok, after a little while of that Gamera will just walk up and beat MG to a pulp. But wasn't that fun to think about, guys?