In short, no.
To elaborate, it faces some big issues. Mega Rayquaza is a far better mega, sporting better coverage, speed, and awesome setup in DDance, as well as the ability to hold an item and occasionally even run a mixed set. It’s versatility makes it excel as a premier threat in the tier, making it a very valuable mega to have. There’s also Zacian-Crowned, an amazing attacker in the tier, sporting even higher attack than Mega Mawile (assuming you have Adamant), better coverage, the same STABs, and far superior speed, as well as overall superior defenses. It’s basically a direct upgrade to Mega Mawile.
Also, Mega Mawile struggles to break past Necrozma-Dusk, a huge threat.
Source:Experience
(PS mega Mawile isn’t even on the Viability Rankings)
