Exeggutor vs Venu vs Jolteon

I'd use Exeggutor on water types over Venusaur anytime.

Solar Beam Eggs still probably fastest against Vaporeon vs. any grass type...

https://www.youtube.com/watch?v=O73CuJpDEqM

against slowbro.

1. Exeggutor is very good for beating Poliwrath. Alakazam can take down Poliwrath faster, but he won't survive more than several Bubbles from Poliwrath - very fragile against the powerful Bubbles.
   So Exeggutor is, by far, a fantastic choice to take down a row of Poliwrath.
2. Best counter against Vaporeons is not Venusaur, but Dragonite. Dragonite takes down Vaporeon faster, resists water attacks, and has higher DEF base stats than Venusaur.

Dragonite is a better Vaporeon counter; Exeggutor is a better counter against water types than anything available. His ATK is so beast, and with Solar Beam he is going to destroy any water types.

Against any Psyc and Water type ....