Which ability for my Torterra?

Question

His moveset will be:

• Seed Bomb
• Earthquake
• Stone Edge
• Curse

I plan on EV training him with 252 Attack/128 Defense/128 Special Defense

I don't know whether Overgrow or Shell Armor will be more beneficial.

Answer 1

For you, Shell Armor. We wouldn't want a crit when setting up Curse, would we?
Overgrow would work also, but Shell Armor is the superior choice here.