Help beating Final XD boss(Greevil)

[Big Mystery Fan]

Even tho I have yet to battle the final boss I have my doubts of how long I could last in the battle.

Here are my party pokes.

Umbreon Level 52

ATTACK: 95 Shadow Ball
DEFENSE: 143 MoonLight
SP. ATK: 82 Faint Attack
SP. DEF: 166 Psychic
SPEED: 101

Ninetales Level 43

ATTACK: 81 Heat Wave
DEFENSE: 75 Flamethrower
SP. ATK: 93 Attract
SP. DEF: 103 Dig
SPEED: 118

Sandslash Level 43

ATTACK: 105 Brick Break
DEFENSE: 105 Fury Swipes
SP. ATK: 67 Slash
SP. DEF: 61 Earthquake
SPEED: 71

Cloyster Level 44

ATTACK: 85 Spike Cannon
DEFENSE: 179 Refresh
SP. ATK: 91 Surf
SP. DEF: 59 Ice Beam
SPEED: 83

Jumpluff Level 42

ATTACK: 58 Poisonpowder
DEFENSE: 86 Solarbeam
SP. ATK: 62 Giga Drain
SP. DEF: 83 Leech Seed
SPEED: 103


Electabuzz Level 43

ATTACK: 90 Fire Punch
DEFENSE: 66 Thunderbolt
SP. ATK: 88 Cross Chop
SP. DEF: 87 Thunder
SPEED: 112


I switch in between with this one constantly

Fearow Level 43

ATTACK: 103 Mirror Move
DEFENSE: 68 Baton Pass
SP. ATK: 64 Drill Peck
SP. DEF: 65 Aerial Ace
SPEED: 99

Might I need to change my pokemon, my attacks or level up alot?

 

[Sydian]

Use the Spin-offs Q&A. Also, if you've already Snagged shadow Lugia, take that in there with you. It'll help since shadow attacks are super-effective on normal Pokemon.