I'm about to start breeding for a Mega-Heracross. Which nature is better? Adamant, or Jolly? His base speed isn't great, but his attack is through the roof. I've seen people invest in speed EVs, so would it be best to go for max speed to compensate? What could he typically outspeed, with or without +speed nature?

I may use him in singles and doubles; not sure if I'll go with my Baton Pass Scolipede in the same mix, or not. I'm thinking of this set:

-Pin Missile
-Bullet Seed
-Rock Blast
-Bulk Up/Close Combat/Brick Break

Thanks!