Was the guy stupid, a bad player, brainless, had a brain but just didn't use it or did Battle Spot change its mind and decide to love me again?
From my calculations your mega salamence would have a speed stat of 124.
Gardevoir base speed is 80 and at highest is 93-145 so the guy you faced probably didn't use timid or have make speed evs invested at a neutral nature it would be between 85-132
Breloom has base 70 speed and at highest would be 82-134 probably running adamant
Hope I helped