Another event question, magikarp, puff or growl?

I vote for Growlithe but if they are low cp i wouldnt use dust to pwer them up, just for the pokedex.

Thou maybe magicarp would be best option if they all just go for pokedex?

I am bias towards wigglytuff but I think you can find a better one to evolve. The growlithe and magikarp would net you some pretty strong pokemon if evolved. I'd say Magikarp first, but farming them right now during the event is way easier than farming growlithe. Just find a body of water and you should see some

If you evolve that low cp pokemons and the get bad Moveset it will be worst, be patient and wait for a higher Cp with good IV

Growlithe in my opinion.

Gyarados is not a strong pokemon in my eyes. The double electric weakness makes it useless on defense, while it's outclassed in offense by many common pokemon (e.g. Vaporeon). 400 candies to evolve? You'll get there eventually (you can get 80 in a day trip to a beach next summer...) and there's no rush to do it now.

Arcanine on the other hand can be a top tier attacker. Maybe you'll want to hatch a stronger Growlithe, but either way it'll be a nice addition. Without a consistent Growlithe spawn point, you'll likely wait a lot longer to get one unless you happen to hatch 2 or 3 quickly.

Puff isn't bad to walk outside of the event. Wigglytuff can also randomly spawn a lot more in my experience than Arcanine/Gyarados would. So I'd vote against her as well.

I'd also consider Exeggcute if you haven't evolved it yet and they don't spawn frequently for you.

Dont put makicarp as buddy.
As you want growlithe or jigly, the rarest where you are.

Evolve the jigly, you wont find another almost perfect IV one. And hope for good moveset. Low cp isnt a matter, candies are easy to get (1km, 250 for 1 week) and investing dust if good moveset is not a waste because it will me a monster

Since Arcanine is an attacker, IV doesnt really matter, wait for 900-1000cp growlithe and evolve it.