ITT: Fine-tune fake Mega ideas so that they're decent, but not overpowered

Mega Forretress @ ShittyMSPaint-ite
+20 Attack
+40 Def
+40 Sp. Def
-10 Speed
-50 Artistic Skill
And knowing Game Freak, probably a useless +10 in Sp. Attack

Ability: Gunpowder (Or Blackpowder, don't wanna offend any soccer moms with the word "gun")
>Upon entry, all Pokemon on the field become covered in Powder.
So basically think Intimidate, but with Powder.

Too broken? I'm always leery of making up abilities, but Flash Fire would have been kind of a stretch for Forretress.