100% Tentacool: should I evolve?

I wouln't evolve him. His CP are too low.

I know it's really really really rare, but don't spend stardusts on it. Its base stats are not that good.

Lorma96,
While you are still catching lots of Tentacools, don't evolve any of them or power any up. Wait for "neo" (the one).
Try to be patient and wait to catch "neo".
Once the area around stops spawning tentacools you then can evaluate your inventory and make the best choices.

Perfects are rare, usable perfects are very rare. Most of mine are garbage(ratticate, arbok, onix, etc). It does have the cool collector value to it. The game is kinda lame if don't power cool mons, at least in my opinion.

It really depends on your dust though, maybe set it on the back burner and see how the next event goes dust wise.

I like Tentacool as a defender (Poison Jab/Blizzard) but if your stardust is low I'd wait until you have spare dust and candies.

I'd say yes. Tentacruel is a cool and different pokémon. It's outclassed by some others, but it's not weak.

100%'s are never a waste anyway.

It depends for what u will use Tentacruel.
I have 3 of them with poison jab - hydro pump and ivs 93,93,96.
I only use one for offensive/training of gyms. The max cp is too los to use it as defender in gyms in my area. Some gyms start at 2600cp and you don't want to end up in the bottom after training.

It also depends on your area. In my area they arent that rare. What is really rare for me is Grimer (although I have 2 Muks)

Hell yes, evolve it!
While you have a local nest, and therefore candy to do so.
After you've evolved it, you can let the resulting moveset determine whether it's better to power it up or keep it low.

Evolve it and see what you get, what else are those candies going to be good or used for? Then I would see what move sets you get before deciding on if you are going to spend stardust on it.

What is the best moveset that you are hoping for on Tentacruel? Unless you for some bizzare reason have a lot players putting Faeries into gyms in your area, it is not going to be one of your top attackers. Tentacruel is a coop defender, but crippled by low max CP, in which case you want as high IVs as possible. Evolve it, hope for a good defensive moveset, then favorite it and wait to power it up later.

Agree with the others, but 100% is pretty rare and I still haven't found one yet (lvl 28).

I think putting it on the back burner is probably the best idea, at least till the Christmas/holiday announcement is out.

After that, maybe evolve it and if it has the best movesets (HP or Blizzard), then consider powering it up afterwards.

A lot of people say to wait for every mon (both high level and high IV), but if you don't use dust much (I'm now sitting on 600k), the problem for me is nothing to really power up. Dust is guaranteed to come in while IVs aren't really...

Part of me is sorta regretting not using the Eevee name trick on a 98% Eevee that was only lvl 10 way back (it turned into a Jolteon for me).

After all these levels, still no high IV Eevee and Vaps are great in gyms now. I still don't have any high IV defenders so sorta locked out with 2600 gyms in my area now (Rhydons/Vaps/Snorlax...).

Too bad gym placement is by CP, really hoping they change it to Pokemon level or something else since we're now seeing the same 5 again.

I say dooooeeet! You don't have to immediately power up after you evolve it. Evolve poop moves keep it as a trophy and no dust wasted. Get a good moveset wait until you've farmed up enough dust to raise.