IMO
medicham isnt quick enough to sweep
&
mawile isnt tough enough to be a wall
im not saying they are bad pokemon, but
this leaves them both outclassed for online play
Don't be so sure of this; you're underestimating what Mega Medicham and Mega Mawile can do.
100 Speed, while not the best Speed benchmark to have, is a big step up from base 80 Speed, making Medicham more effective as an attacker.
Mega Mawile's HP may still be at 50, but its good defensive typing, Defense of 125 and Special Defense of 95 are enough to compensate for it. Because of this, it can take a hit easily and retaliate with strong physical moves.