Metronome is a terrible move to use competitively.
In-game, it's an absolute hoot to use.
Me First is bad as well. What if they use a status move? That would suck.
Transform isn't reliable, and shouldn't be used competitively either.
Here's a Mew set I would use:
Mew @ Leftovers
EVs: 252 HP / 104 Def / 152 Spe
- Knock Off