Since this is competitive, I strongly suggest that you replace Withdraw for something more resourceful, like Calm Mind.
The last move can be one of the following:
- Scald: Top alternative in my opinion. Calm Mind further boosts the amount of damage you can do, and the burn chance is handy. Also a reliable secondary STAB move.
- Flamethrower/Fire Blast: For the likes of Ferrothorn, and in general good coverage. It does better replacing Psychic though.
- Ice Beam: Covers the Grass weakness that MegaBro suffers from. Again, does better replacing Psychic.
I suggest you go for Scald, as it's pretty much staple on any stalling Pokemon, and even more on a Calm Mind user.
Hope I helped!