Will an agility speed up M Heracross to a decent amount?

Question

Because I am thinking of using a Hawluncha to use Agility, then use Baton Pass to pass on the speed boost onto Heracross.

Answer 1

Yes, it would be useful, because Heracross' speed will be doubled when it is Baton Passed the speed boost

Heracross will be super fast if it is a jolly nature and his base speed will be basically 150 instead of 75, like Sep said.
I know you probably have your own set for Mega Heracross, but here's a suggestion:

Heracross @Heracronite
Trait: Moxie ---> Skill Link
Jolly Nature
EVs: 252 Atk, 252 Spe, 4 Def
-Pin Missile
-Rock Blast
-Bullet Seed
-Close Combat

Also you might want to change your Baton Passer to Ninjask or Scolipede instead of Hawlucha. Hawlucha can do so much more instead of being a Baton Passer. Ninjask or Scolipede would be so much better instead of Hawlucha. But if you making a mono fighting team, which explains having 2 fighting types, then go ahead and keep Hawlucha as your Baton Passer.

Hope I helped!

Answer 2

It depends on what your definition of "decent" is.

Using agility will raise the user's speed by 2 stages (100%) which is two times the user's speed before it used Agility. Mega Heracross's base speed is 75, if it gets a two stage speed boost it's speed will go up to 150. (If I'm correct on how speed works)
If you think 150 speed is decent then yes, an Agility will raise Mega Heracross's speed to a decent amount.

Hope I helped!