Dubwool can wall pretty much most common physical attackers with Cotton Guard set up. Fluffy is better in that it covers more moves but is detrimental against Fire moves. Bulletproof is a much more niche pick but can be useful against Sludge Bomb/Aura Sphere/Gyro Ball but is usually not good as Fluffy. Cotton Guard and Body Press lets Dubwool deal nice damage with Payback to cover against Ghost types. Payback would usually want Dubwool to have the least Spe as possible. Substitute is better in most situations but Dubwool can be run with Grassy Glide + Grassy Terrain + Grassy Seed. 80+ Def can guarantee a 4HKO from Mega Lucario's Close Combat to cover extra special bulk but 252 HP 252 Def can be run as well.