Torterra
Moltres struggles against Rock-types such as Omastar, Kabutops and Rhydon, while also being vulnerable to fast Choice Scarf wielding Electric-types such as Rotom
Torterra can demolish Rock-types with either of its STABs, is immune to Electric, and can easily take Rock-type moves while also supporting Moltres with Stealth Rock. Moltres can take Fire and Bug-type attacks for Torterra.
Torterra (M) @ Leftovers
Trait: Overgrow
EVs: 212 HP / 252 Def / 44 Spd
Impish Nature (+Def, -SAtk)
- Stealth Rock
- Seed Bomb
- Earthquake
- Synthesis
This is the more tankish set, although Torterra can also run more offensive variants. Although Moltres needs spin support, personally, I think that we should avoid choosing a spinner so soon as it restricts teambuilding later on.