Ok, I've used this guy for a long time in various situations before, and I want to let him out now. Harvest Lum Exeggutor is just amazing IMO. I've used him in OU in the past even - to some good extent - and in the lower tiers I imaigne he does even better.
Exeggutive (Exeggutor) (M) @ Lum Berry Trait: Harvest
EVs: 4 Def / 252 SAtk / 252 SDef
Bold Nature (+Def, -Atk)
- Rest
- Psyshock
- Giga Drain
- AncientPower
This guy is a tried and tested success. What I originally found him on was the ability Harvest. Don't give me "subseed sitrus tropius", because seriously, that thing is a piece of crap. Exeggutor actually hits stuff and isnt stopped by every grass type in the game. With harvest, I wanted to turn Exeggutor into the perfect stall breaker, because at the time I was having some blissey problems. Harvest Lum is simply amazing. He laughs at parahax, toxicstall, and WoW users. In actuality, he is a perfect counter to blissey, resisting every status, resting off the seismic tosses, and 2HKO/3HKOing with Psyshock.
First, the EV's and Nature. Exeggutor with harvest lum is literally immune to every status in the game permanently bar curse, infatuation, and flinch. Being grass type is a great boon to stop subseeders as well. Now, with that kind of immunity, I wanted him to last and live. So I poured EV's into SPDef and Def, admiring his good HP stat without investment. Now, he can take a hit, having average bulk. Rest is a perfect move on this set for survivability, harvest lum completely waking him.
Second, the offensive adjustment. Exeggutor was again a better go to than tropius because I was drawn by his fantastic SPAtk stat. He hits 349 with this set, and packs quite a punch. Giga Drain is a great STAB with its power boost in 5th gen, and greatly increases survivability in battle when he's gaining back HP while attacking. Psyshock is another good STAB, killing the fighting types running around, and especially being there for blissey, annoying blissey.
Last, the perfect tie in. Ancientpower. Ancientpower seems to be a lackluster move on pokemon that don't get STAB on it, and frankly you may wonder why it's here. Again, tried and tested in many many battles, ancientpower is the true glue that binds the set together in the end. First off, it is a fantastic type coverage to hit his weaknesses, killing fire, bug, and flying switches that are unsuspecting. But mainly, it's the boosts. Now, 10% isn't much, and you may well wonder why I'm crazy enough to run it for that. But in nearly all of the situations I battled in with Exeggutor, I managed to get at least 1 Ancientpower boost off in the battle. 1 boost turns Exeggutor into a tanky pokemon, with 340~ defenses, and a fantastic 500~ sp att. If you get 2 boosts, its pretty much game over. The situations to get these boosts are relatively simple. You bring exeggutor on a wall or stall pokemon, lol @ status moves trying to stop you, hit them with ancientpower until they switch, and probably have a boost by then to wreak havoc. Ancientpower really completes this set, and is fantastic for him.
I really love this set, it's been a long used one by me and very successful in many battles. I can't vouch for using him in OU, as he's probably not going to fare well in it, but in UU and definately RU, he can most likely shine. But for his time in OU, I do want to say that he killed every Blissey and Jellicent that dared stand in front of him. He is an amazing stall breaker.
Edit: Please note that there was a bug with Harvest a while back, where it would activate 100% every turn. It has been fixed, Harvest only works 100% every turn while SUN is up, and 50% out of SUN. Now, do not worry about this, because I have played with him more after this fix, and there is really not much of a difference. Scrafty and other pokemon have Shed Skin, which removes status moves 33% of the time every turn, and they are very good abilities and in fact activate quite often. Exeggutor's Harvest Lum outside of SUN has a 50% activation chance per turn, much more than Shed Skin. It is merely the flip of a coin, and so you don't have to worry about this chance messing up his status immunity. In most cases, losing 3/16th of your health from toxic because harvest won't activate for 2 turns isn't game breaking at all, and barely matters to you. Worst case scenario is that you lose 1 or 2 turns from rest. I have definitely tested him enough with this 50% effect to feel that it is a reliable security still.