If you need some extra power while you're out hunting down those Pokemon, then the Anker PowerCore 10000 is a great one to pick up. This isn't the Quick Charge 3.0 model, but it does feature the company's PowerIQ Technology, which will still charge your smartphone pretty quickly. It's a fairly small battery pack, making for a great companion when you're out hunting down Pokemon, as you can stick the battery pack in your pocket and keep your phone in your hand and capture that Drowzee. There's just one USB port included here, so you won't be able to charge your friends phones at the same time. However, you will be able to charge your phone around three times or so, depending on the size of the battery inside the phone that you are using (many are 3,000mAh or smaller). This battery does also work with iPhones, since it just requires a USB cable.
Currently, the Anker PowerCore 10000 is the world's smallest battery pack with 10,000mAh capacity. It's also one of the lightest battery packs around. Making for a great companion. Anker currently has this one on sale over on Amazon for just $25.99. Definitely worth picking up if you're addicted to Pokemon GO, like just about everyone else out there right now.