Judge my OU team

[Kakarot1212]

Hey guys! So this is my first "Team help". And I'm longing for some recommendation on how to improve my team.
Without further ado:

Mawile @ Mawilite
Ability: Intimidate
EVs: 252 Atk / 252 HP / 4 SDef
Adamant Nature
- Sucker Punch
- Play Rough
- Foul Play
- Pain Split

Gyarados @ Leftovers
Ability: Intimidate
EVs: 252 Spd / 252 Atk / 4 HP
Adamant Nature
- Waterfall
- Earthquake
- Dragon Dance
- Stone Edge

Salamence @ Dragon Fang
Ability: Moxie
EVs: 252 Spd / 252 Atk / 4 SDef
Adamant Nature
- Dragon Dance
- Dragon Tail
- Dragon Claw
- Roost

Mandibuzz (F) @ Leftovers
Ability: Overcoat
EVs: 252 Def / 252 HP / 4 Atk
Lax Nature
- Air Slash
- Roost
- Foul Play
- Toxic

Forretress @ Rocky Helmet
Ability: Sturdy
EVs: 252 Def / 252 HP / 4 Atk
Relaxed Nature
IVs: 0 Spd
- Rapid Spin
- Spikes
- Pain Split
- Stealth Rock

Greninja @ Expert Belt
Ability: Protean
EVs: 252 Spd / 252 SAtk / 4 Atk
Hasty Nature
IVs: 0 Spd
- Dark Pulse
- Hydro Pump
- Ice Beam
- U-turn

This team brought me to many victories, but i want to improve it.
I'm very open for recommendations.

Thanks in advance! :D

 

[PlatinumDude]

I don't think Mawile has time for Pain Split. Mawile is also strong enough that it doesn't need Foul Play (though it does see use in the RestTalk set to compensate for the lack of Attack EVs in that set). It's also slow, so it needs Sucker Punch to make up for its bad Speed:
-Play Rough
-Sucker Punch
-Fire Fang/Iron Head/Swords Dance
-Swords Dance/Substitute
Nature: Adamant
EVs: 132 HP/252 Atk/124 Spe
Item: Mawilite
Ability: Intimidate

or
-Rest
-Sleep Talk
-Play Rough
-Foul Play
Nature: Impish
EVs: 248 HP/252 Def/8 SDef
Item: Mawilite
Ability: Intimidate

Offensive Dragon Dance Gyarados uses Life Orb or Lum Berry as the item. The former gives Gyarados better damage output, while the latter lets Gyarados shrug off a status once.

Salamence has fallen out of favor in the OU environment because of its inability to deal with Fairies apart from the inaccurate Iron Tail. Half of your team is currently weak to Stealth Rock and that's a bad thing. Other Dragon Pokemon to consider are Goodra and Garchomp:

Goodra:
-Draco Meteor
-Fire Blast
-Thunderbolt/Earthquake
-Dragon Tail/Earthquake
Nature: Quiet/Sassy
EVs: 248 HP/252 SAtk/8 SDef
Item: Assault Vest
Ability: Gooey/Sap Sipper

or
-Draco Meteor
-Fire Blast
-Thunderbolt
-Focus Blast
Nature: Modest
EVs: 248 HP/252 SAtk/8 SDef
Item: Choice Specs
Ability: Gooey/Sap Sipper

or
-Dragon Pulse
-Flamethrower
-Thunderbolt
-Toxic/Dragon Tail
Nature: Calm/Sassy
EVs: 248 HP/8 Def/252 SDef
Item: Leftovers
Ability: Gooey/Sap Sipper

Garchomp:
-Swords Dance
-Outrage/Dragon Claw
-Earthquake
-Fire Fang/Stone Edge
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Life Orb/Lum Berry/Yache Berry

or
-Outrage
-Earthquake
-Fire Fang/Aqua Tail/Stone Edge/Fire Blast
-Dragon Claw/Dual Chop
Nature: Jolly/Naive
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Band/Choice Scarf

or
-Stealth Rock
-Outrage/Dragon Claw
-Earthquake
-Fire Blast/Toxic
Nature: Impish
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers/Rocky Helmet
Ability: Rough Skin

Mandibuzz is one of the best Defoggers out there. If I were you, I'd take advantage of that fact. Lax is also a terrible nature to use competitively, as it wastes away Mandibuzz's good Special Defense. Take note that Foul Play doesn't use Mandibuzz's Attack; it uses the opponent's Attack to calculate damage:
-Foul Play
-Roost
-Defog
-Toxic/Whirlwind/Knock Off
Nature: Bold/Impish
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
Ability: Overcoat

Forretress is rather subpar now. The better hazard setters to use are Ferrothorn and Skarmory:

Ferrothorn:
-Spikes/Stealth Rock
-Leech Seed
-Gyro Ball/Thunder Wave
-Power Whip/Protect
Nature: Relaxed
EVs: 252 HP/48 Def/208 SDef
Item: Leftovers
Ability: Iron Barbs

Skarmory:
-Roost
-Whirlwind
-Stealth Rock/Spikes/Brave Bird
-Defog/Brave Bird
Nature: Bold/Impish
EVs: 252 HP/252 Def/4 SDef or 252 HP/16 Def/240 SDef
Item: Leftovers/Rocky Helmet
Ability: Sturdy

or
-Spikes
-Roost
-Whirlwind
-Taunt/Brave Bird
Nature: Bold/Impish
EVs: 252 HP/184 Def/72 Spe
Item: Leftovers/Rocky Helmet
Ability: Sturdy

 

[Nah]

Mega Mawile doesn't need Foul Play since it has Sucker Punch, and can't make use of Pain Split because its not bulky enough for it. So yer gonna wanna replace those moves with Swords Dance and Fire Fang.

All Dragon attacks on Salamence=walled by Fairies. Dragon Tail is for phazing, but Salamence is an offensive poke. So give it Earthquake.

Air Slash isn't needed on Mandibuzz. Foul Play/Knock Off is the only attack she needs since she's more of a wall. Taunt is a good option in that slot. And Impish would be the better nature here.

Forretress prefers Leftovers since it only has Pain Spilt as pseudo-recovery. Rocky Helmet works better on pokes that have Iron Barbs or Rough Skin to increase the contact damage. Most people don't hit Forretress with contact moves anyway; most contact moves are physical attacks and Forrtress has high Defense, so people usually hit it with special attacks. Also, there's little need to have 2 hazards on it. Your current moveset makes it set-up fodder and is useless after the hazards are lain. So pick one and give it Volt Switch or Gyro Ball.

Life Orb is better on Greninja so all of its attacks get boosted all the time. And you don't want 0 Speed IVs on it.

EDIT: Dammit, I though I was done being ninja'd....

 

[Kakarot1212]

Thanks for the recommendation! I'm going to give it a try. ^^