Why use Megahorn instead of Pin Missle? Mega Heracross's Pin Missle is stronger, more accurate, and has more PP than his Megahorn. In addition his Pin Missle is a multi-hit move (unlike his Megahorn) which means that his Pin Missle can beat certain strategies that his Megahorn cannot beat like some involving Substitute.
Pin Missle is objectively superior to Megahorn in this case so why did you go with Megahorn?
On top of that why 2 fighting moves? Do you like having bad coverage? Flying resists both your STABs and you have a 125 BP multi-hit 90% accuracy Rock move available yet you opt for a second Fighting move instead.
You should probably base your teams on more than just comparing offensive stats.