Exeggutor @ Sitrus Berry
Trait: Harvest
Evs: 252 Hp / 252Atk / 4Spe
Adamant Nature
-Substitute
-Wood Hammer
-Zen Headbutt
-Swords Dance
Exeggutor posseses a surprisingly decent base 95 Attack stat, and a powerful STAB combination that is only resisted by Mawile, Exeggutor, Cacturne and Skuntank allows him to muscle past many of his usual checks, like Gardevoir. The crux of this set is the combination of Harvest, Wood Hammer and Substitute - Harvest allows Exeggutor to recover off its recoil free of charge, and Substitute allows Exeggutor to eat hits that would otherwise take advantage of its poor speed. Zen Headbutt, aside from obligatory STAB, lets Exeggutor shoulder past Amoonguss, a Pokemon that gives many other physical Pokemon, including fellow Wood Hammer user Torterra, pause. Once it gets a Swords Dance or two up, very little can take a hit, and Exeggutor outspeeds the few that do (Torkoal, Lairon). HP EVs increase its bulk, making Substitutes sturdier and Harvest returning more health, and it also lessens the impact of recoil. Because of a poor base Speed, Exeggutor greatly appreciates paralysis support, allowing it to throw out multiple Substitutes in conjunction with Harvest, gambling on a paralysis chance to allow it to setup.
A few quick calcs:
+2 252+ Atk Exeggutor Zen Headbutt vs. 248 HP / 252+ Def Torkoal: 132-156 (38.48 - 45.48%) -- 89.06% chance to 2HKO after Stealth Rock.
+2 252+ Atk Exeggutor Wood Hammer vs. 252 HP / 200+ Def Torterra: 252-297 (63.95 - 75.38%) -- guaranteed 2HKO
+2 252+ Atk Exeggutor Zen Headbutt vs. 252 HP / 0 Def Braviary: 294-346 (72.77 - 85.64%) -- 81.25% chance to OHKO after Stealth Rock
+2 252+ Atk Exeggutor Wood Hammer vs. 252 HP / 252+ Def Gardevoir: 325-384 (95.58 - 112.94%) -- 75% chance to OHKO
+2 252+ Atk Exeggutor Wood Hammer vs. 252 HP / 112 Def Lickilicky: 322-379 (75.94 - 89.38%) -- 12.5% chance to OHKO after Stealth Rock
+2 252+ Atk Exeggutor Zen Headbutt vs. 252 HP / 0 Def Miltank: 222-262 (56.34 - 66.49%) -- guaranteed 2HKO
+2 252+ Atk Exeggutor Zen Headbutt vs. 252 HP / 252+ Def Eviolite Tangela: 102-120 (30.53 - 35.92%) -- guaranteed 3HKO after Stealth Rock
Tangela (which nobody runs anymore) is the only thing that can reliably take a hit, and even that is shut down after two or more Swords Dances.