u/Delicious_Morning_42

Yeah Gru was able to find success as a villain because for most of it he mostly stole artifacts and barely ever fought anyone else unlike Megamind who was facing off against a big fish in his own universe. Even if megamind wanted to not want to treat his rivalry with metroman as a game and decided to take him seriously he would still lose no matter what because metroman is just way too powerful for him to deal with. Gru never fought anyone similar to metroman as a villain and the people he did face pale in comparison

In the first movie when minion disguised as megamind he uses a de-gun on the metal bar. And when he is knocked out he uses a holo-watch to revert back to his form while megamind uses another watch to be metroman. Megamind never seems to take the de-gun minion has when he chases tighten away either, and he was already carrying one after reverting back from his disguise of metroman. So it is implied minion has his own de-gun that he could easily use against Gru that might also have the different modes megamind’s one has