The team:
 
P (Pikachu) (M) @ Light Ball
Ability: Static
Level: 50  
EVs: 4 HP / 252 SpA / 252 Spe  
Modest nature  
IVs: 31 HP / 2 Atk / 30 Def / 31 SpA / 31 SpD / 31 Spe  
- Thunderbolt
- Hidden Power [Ice]
- Surf
- Thunder
 
C (Charizard) (F) @ Lum Berry
Ability: Blaze
Level: 50  
EVs: 76 HP / 252 Atk / 180 Spe
Adamant nature  
IVs: 31 HP / 31 Atk / 31 Def / 31 SpA / 31 SpD / 31 Spe  
- Aerial Ace
- Earthquake
- Belly Drum
- Brick Break

M (Metagross) @ Quick Claw 
Ability: Clear Body
Level: 50  
EVs: 4 HP / 252 Atk / 252 Spe  
Adamant Nature  
IVs: 31 HP / 31 Atk / 31 Def / 31 SpA / 31 SpD / 31 Spe  
- Meteor Mash
- Earthquake
- Shadow Ball
- Explosion

Notes:
- Lead Pikachu in rounds 1-3, Charizard in round 4
- 143 Speed for Charizard outspeeds base 100s in round 4
- Linoone might be better than Charizard, but it has to sacrifice bulk and coverage to beat Greta's Heracross
- Metagross is basically never used, but it helps for Gold Symbol attempts