Should I evolve this or power up? [duplicate]

Your Poliwag will evolve into a Poliwhirl with ~485 CP. So it makes no sense to evolve it. It'll be cheaper to keep the current one and feed 1-2 candy later on.

Anyway, it's usually better to wait. In this case I'd wait for enough candy to get a Polywrath. Don't evolve too soon. Always wait until you have the ressources to evolve the Pokémon to its final stage. This way you can evolve the best Pokémon you currently have and don't risk evolving a weak one when you still have the chance to get a better one while farming candy. Maybe you even find a Poliwrath to spend your candy on.

I would suggest you avoid Powering up anything until you're certain that you are going to use that pokemon. Afterall, you need a lot of stardust to fully upgrade 1 pokemon.

Evolution on the otherhand is somewhat different (with exception of Magikarp).

• If you think you can catch 15~20 without putting much effort in, then you can easily get candy and essentially make those pokemon evolve for "free".
• If you only see 0-3 of it per day, then getting candies when you need them might be hard, in which case I would suggest to hold back on evolving until you're certain you're gonna use the pokemon.

Few notes:

1. You get stronger pokemon when your character is higher level
2. Pokemon CP is only representation of it's current "Power", they have hidden growth rates which means you can have 2 Poliwhirls and 1 of them can have double the CP at the same level. (look into Individual Values (IV) for details)
3. Reason I say you shouldn't power up: Look into final CP you can get by fully upgrading a pokemon. At this point 1000 CP is on the low side of what most people have and if you live in an area where the game is popular you really need to make sure that your pokemon can pass those numbers or it might end up being useless. (Again, you can look at pogotoolkit website to estimate max CP and look into IVs to figure out how powerful your pokemon can get)