How about a kirby boss? At the start, it's a reskinned pink heavy, but when he attackes a class, he get's a weapon that's specific to that class. Things like the scout's sandman with four balls, a sandvich that gives him ten seconds of uber, a single charge with the sheild, flare gun, ect. Afterwerds he would return to the heavy. This boss wouldn't have a rage, and superjump would instantly recharge. (Because kirby floats)