Yes, it's a fantastic Pokemon. Not as broken as Mega Salamence, but still a very threatening Pokemon. It may be frail, but it has everything it needs to be a threat in OU. If you play ORAS OU on Showdown you'll see plenty of people using it.
- It has a fantastic ability in Adaptability, which makes STAB 2x instead of 1.5x. So it's essentially a Choice Band boost for its STAB moves. Stack that on top of its insane attack stat, and you have a real offensive threat.
- It is one of the fastest Pokemon in the game. It reaches a peak of about 420 Speed, which places it above popular OU threats such as Greninja and the Lati twins. This allows it to function as a revenge killer as it moves before basically the entire unboosted metagame.
- Access to a good set of moves, including U-Turn, which allows it to deal damage and get out. It also gets Drill Run, which handles lots of Steel-type switch-ins, particularly Heatran who otherwise walls it completely.
Even though it's frail and weak to Stealth Rock, Mega Beedrill is a very effective late-game cleaner. Once all the broken Megas are out of the tier, Mega Beedrill will stand out as one of the better Megas in OU.
Smogon analysis and movesets