Swampert (M) @ Leftovers
Trait: Torrent
EVs: 252 HP / 80 Atk / 176 SAtk
Quiet Nature (+SAtk, -Spd)
- Earthquake
- Hydro Pump
- Ice Beam
- Rest

Celebi @ Leftovers
Trait: Natural Cure
EVs: 6 HP / 252 Spd / 252 SAtk
Modest Nature (+SAtk, -Atk)
- Baton Pass
- Calm Mind
- Heal Bell
- Psychic

Salamence (M) @ Leftovers
Trait: Intimidate
EVs: 148 HP / 222 Atk / 140 Spd
Adamant Nature (+Atk, -SAtk)
- Dragon Dance
- Earthquake
- Hidden Power [Flying]
- Rock Slide

Houndoom (M) @ Leftovers
Trait: Flash Fire
EVs: 6 HP / 252 Spd / 252 SAtk
Modest Nature (+SAtk, -Atk)
- Crunch
- Flamethrower
- Hidden Power [Grass]
- Pursuit

Forretress (M) @ Leftovers
Trait: Sturdy
EVs: 40 HP / 216 Atk / 252 Def
Impish Nature (+Def, -SAtk)
- Earthquake
- Explosion
- Rapid Spin
- Spikes

Jirachi @ Leftovers
Trait: Serene Grace
EVs: 252 HP / 32 Def / 152 Spd / 74 SAtk
Bold Nature (+Def, -Atk)
- Calm Mind
- Psychic
- Substitute
- Thunderbolt


Here it is. This is my best team, and so far, the win to loss ration is about 100:2.

Bring
Up
My
P Rooster

Farely good team, acutally.

Nice team

If u want a good Celebi counter, use HP Bug on Forretress instead of Earthquake or Explosion. Try to get Forretress' defense to 396 and his attack to 254.
I put the rest of his EVs into HP.

You seem to have a Salamence already to counter Celebi but CBmence is better at it. These are just my suggestions, its your team