All-grass teams are rather risky, as you've to cover 5 types.
Torterra is sturdy to physical hits and takes out fire types, but fears Ice moves like Salamence.
Cradily laughs Poison, Fire and Flying moves off, and has a nice movepool, but is slow.
Tangrowth is physically powerful, but has terrible Special Defense.
Roserade's as close to Alakazam as grass types get, and this comes down to the defenses as well.