Wihch Poliwrath/Exeggutor to Power Up?

Icepunch* on Pwrath for punishing grass attackers when you put him on defense and Solarbeam on Eggy for max DPS.

I dontd know if exeggutor is still the same beast as before the cp update and personally I like poliwrath more. It's just a cool Pokémon. Also ice beam is a good defending move since it will be defending against grass types most of the time (although electrics also play a major role after the update). But why are you asking in the first place? It sounds like you have both Pokémon with all of those move sets. If so, why not power up an exeggutor AND a poliwrath?

I've not fought a Poliwrath to have an opinion. From a pure numbers/logic perspective... Exeggutor or Dragonite is the most logical choice of attacker and Ice Punch does well against both of them.

For Exeggutor i've always found that Solar Beam rarely shows up and telegraphs so much that it isn't worth it on defense. Beyond that, it depends much more heavily on whether they are bringing Ice or Fire/Flying to the party. If they attack with Arcanine, Flareon, Pidgeot, or a bug it is better if you've got Psychic. If they are attacking with a Jynx, Lapras, or Cloyster then Seed Bomb would be better. I'd say Psychic edges out Seed Bomb slightly as Ice Mons aren't as common as Fire/Flying/Bug. Also if there is a Dragonite in the gym, any Ice Mons in the attacking party are going to get sent against the Dragonite and not your Exeggutor.

Are you evolving low cp mons because they have high ivs? And what level are you? 900cp and 800 seem weirdly low

Poliwrath with Ice Punch and Exeggutor with Solar Beam.

Edit: Too low CPs to spend in. What level you are? wait untill 25~28 to start thinking about to power up.