Zamazenta (Hero of Many Battles) @ Scope Lens
Ability: Dauntless Shield
Natue: Jolly (+Spe|-SpAtk)
EVs: 252SpD | 252Spe | 6HP
- Focus Energy: Setup!
- Close Combat: STAB
- Iron Head: Coverage against Fairy Types + 30% Chance to Flinch
- Crunch: Coverage against Psychic Types
Although Crowned Shield form has better Defense and Special Defense, it loses on a crucial 10 stat points in Speed. With Jolly nature, max EVs and 138 base points, it can out speed almost everything. Since Dauntless Shield raises Defense by 1 Stage by default, its a good idea to improve Special Defense, as you need 1 turn for setting up Focus Energy. With Focus Energy and Scope Lens, its Critical-Hit Ratio is boosted by 3 stages which means that every hit will be a critical one (1.5X damage, ignoring opponent's Defense boosts, own Attack loss, Reflect, and Aurora Veil). It already got coverage against 2 of its 3 weaknesses, and the flinch chance on Iron Head might help to take care of Flying types. Now it's time to Sweep!
Most important bit is setting up Focus Energy. It already got good defenses. If you can pit in dual shields, you may even consider moving the 252 EVs from Special Defense to Attack. Or, to be sure, pitch it against a physical attacker to setup and move those 252 EVs to Defense. You may also prefer to have a mixed distribution. It totally depends on how you want to use it and the rest of your team.