I can see you are battling your bro xD
Depends on the team really. Gallade can sweep but the opponents can play around it as it isn't very fast neither does it have much defense. Mega Salamence is kind of the opposite only more powerful and a better chance of setting up with Intimidate.
Personally, I would use Mega Gallade in singles and Mega Salamence in doubles.
A good set for Gallade:
Gallade @ Galladite
Nature: Adamant/Jolly (speed or power depends on you)
Ability: Steadfast ---> Inner Focus (get a speed boost off before mega evolving)
EVs: 252 Atk/252 Spd/4 Hp
-Swords Dance/Knock Off
-Close Combat/Drain Punch
-Psycho Cut/Zen headbutt
-Ice Punch/Thunder Punch
I found the first set of moves to work really well until I switched out my mega.
A good set for Salamence:
Salamence @ Salamencite
Nature: Jolly (enough power so invest in speed)
Ability: Intimidate
EVs: 252 Atk/252 Spd/4 Hp
-Dragon Dance/Earthquake
-Return/Double Edge
-Dragon Claw
-Iron Tail/Steel Wing
Return is preferred over Double-Edge seeing as it is a powerful af move with aerilate and no recoil. Intimidate allows at least one DD set up against a physical sweeper most of the time. Last move is whatever you want.
Hope I helped!
-It's a secret!
