New team:

G (Gengar) (F) @ Silk Scarf 
Ability: Levitate
Level: 50  
EVs: 252 Atk / 72 SpA | 184 Spe  
Lonely Nature  
IVs: 31 HP / 31 Atk / 31 Def / 30 SpA / 31 SpD / 30 Spe  
- Shadow Ball
- Thunderbolt  
- Hidden Power [Water]
- Explosion

M (Metagross) @ Metal Coat
Ability: Clear Body
Level: 50  
EVs: 4 HP / 252 SpA / 252 Spe  
Adamant Nature  
IVs: 31 HP / 31 Atk / 31 Def / 31 SpA / 31 SpD / 31 Spe  
- Meteor Mash
- Earthquake
- Aerial Ace
- Explosion

S (Slaking) @ Choice Band
Ability: Truant
Level: 50  
EVs: 252 Atk / 4 SpD / 252 Spe  
Adamant Nature  
IVs: 31 HP / 31 Atk / 31 Def / 31 SpA / 31 SpD / 31 Spe  
- Return
- Shadow Ball
- Hyper Beam
- Earthquake

Routing notes:
- Metagross/Latios are optimal for Greta 2
 
Ideas:
- Metagross (Adamant @ Quick Claw, Meteor Mash/EQ/Shadow Ball/Explosion)
- Latios (Modest @ Lum Berry, Psychic/TB/Surf/DC)
- Slaking (Adamant @ Choice Band, Return/Shadow Ball/Hyper Beam/EQ)