Masquerain

Intimidate
Lowers the foe's Attack 1 stage. Decreases wild encounter rate.
Type Tier
Bug / Flying NU
Statistics
Min- Min Max Max+
HP
70
- 281 344 -
Atk
60
140 156 219 240
Def
62
144 160 223 245
SpA
80
176 196 259 284
SpD
82
180 200 263 289
Spe
60
140 156 219 240
Name Item Nature

Special Attacker

Leftovers / Petaya Berry Modest / Timid
Moveset EVs
~ Stun Spore
~ Ice Beam
~ Hydro Pump
~ Giga Drain / Substitute
4 HP / 252 SpA / 252 Spe

Only moveset good for it. Masquerain will have to Stun Spore everything in sight. The huge problem with Masquerain is its movepool. It has absolutely no attacks that corresponds with it Special Attack, its best offense stat. Substitute will probably be the best filler for that annoying last move, but Giga Drain can screw something. It won't do much, and don’t expect it to get a K.O. in the early stages of the game.

Other Options

Don't even try Toxic + Protect set. You won’t get anywhere with that. Stick with the script and use Stun Spore.

EVs

Just go with max Special Attack and Speed.

Opinion

Masquerain can't do any damage, and it's not worth it at all. Please, you're better off with Butterfree and Ledian. If you were dared on using this, or maybe perhaps you lost a bet, the only thing you need to know about is to Paralyze as much as you can, and if you have the sure fire way to OHKO, even though chances are it can't, go for it.

Counters

Anything. Masquerain will need luck in order to kill something, but your opponent won’t need that luck at all to take this down.