exeggute question

Yes, it is. Low defense hurts, but exeggutor can take a hydro pump without fainting.

I have no good venusaur (witch would be my prefered attacker into vaporeon), and so i use my Exeggutor (2500 CP, same moveset as yours), and it works great.
If it is just one vaporeon to beat, I don't need to dodge at all, if i dodge charged attacks, i can make two Vaporeon faint.

If killing Vapes is a your only purpose, than it will definitely do the job, so you can power it up I assume.

Can be a good backup choice against a Rhydon without Megahorn also. Grass resists ground, psychic resists fighting, but grass/psychic is doubly weak to bug.