I just tried the custap/harvest set that was mentioned earlier in the thread using regular Exeggutor in a gen 6 match, and honestly, I could see a little potential in it. Replay is here:
http://replay.pokemonshowdown.com/ou-512116650
Now obviously the team I went up against was
FAR from competitive, but I think you can see the potential in the set. For me, it'd go something like this:
Exeggutor-Alola @ Custap Berry
Ability: Harvest
EVs: 252 HP / 252 SpA / 4 Spe
Modest Nature
IVs: 0 Atk
- Draco Meteor
- Leaf Storm
- Protect
- Flamethrower/Substitute
So obviously this set is more gimmick than actually competent, as well as dependent on Gamefreak being kind on our dragon tree friend in the future by actually releasing custap berry in the future. What's cool about this set, is that it's more inclined on revenge killing, rather than straight up sweeping. How it works, is that you invest in as much bulk and Sp.Atk as you can to try and use Exeggutor as a sorta tank early in a game while carefully trying to get him to that 25% hp which is a mixed bag in of itself. From there, you can use him as a revenge killer with +1 priority on crazy powerful bp stabs and flamethrower for good coverage, coming off a base 125 Sp.Atk. What's great is that you can constantly use this throughout the game if you can keep hazards off the field, and can constantly reharvest your berry. Protect is there if harvest fails to activate, giving you another chance at collecting another custap berry.
You could run giga drain/energy ball and dragon pulse(if he eventually gets it) as well as dropping flamethrower for sub, if you want go for the long run, though that only works as a late game sweeper, and is underwhelmed by the fact that Exeggutor has no boosting moves in its Alola form.
For partners, drought users work best, as they give harvest 100% usability, and boost flamethrower's power. Torkoal in particular works well, as he has rapid spin to keep hazards in check, so as to prevent Exeggutor from just coming in and dying immediately. Like I said, this set is absolutely gimmicky/ loses to all priority except maybe aqua jet/ and is outclassed by a lot of other things like chlorophyll users and choice-scarf Pokemon. Really makes me wish the ten points went into anything but the attack stat.
Also, this is my first time actually posting, so sorry if I did something wrong.