Everything works as multiples.
Your Pokemon have three stats:
Health
Defense
Attack
Let's look at Vaporeon for example:
https://pokemongo.gamepress.gg/pokemon/134Water Gun does 6 damage. Its cooldown is 0.5 seconds. So, it does 12 dps (6 damage x 2 attacks per second). You get STAB (same attack type bonus), so it actually does 15 dmg (6 damage x 1.25bonus x 2 attacks per second).
Once you figure our the DPS of your attack, then you have to factor in your character's attack stat. So it does 15dps, but then based on your stats, it will output more. The net damage will be a factor of your attack stat, and your opponent's defense stat, and any weaknesses or whatever.
When you look at something like a charge attack, you have to look at the same stuff, but also how long the attack will last for. An attack that does slightly lower DPS, but lasts much longer, may actually be better on attack or defense. For example, one move may do 20 damage per second over 5 seconds, and may be better than another move that does 30 damage per second over 1.75 seconds (it also depends on how much energy the moves cost).
Some attacks are better for defense. For example, water pulse is the worst attack move, but the best defense move, based on how the AI defends for you.
You can just use the website I linked to view your best attack or defense movesets (they list A, B, C, D tier movesets so you don't have to think much about it). Imo though, some moves are too easily dodged (hyper beam), so on a Snorlax I always prefer body slam as a defense move.
https://pokemongo.gamepress.gg/pokemon-list(Also, primary moves charge up your energy at different rates. So lower DPS may be outweighed by higher EPS... rarely, but sometimes. So just use the list I linked above if you don't want to have to think too too much.)
This post was edited by Canadian_Man on Sep 24 2016 06:01pm