Looking for a group messaging app?

Ok, so I play this game on my iPhone called Marvel War Of Heroes. I'm in an alliance (guild, clan, whatever you wanna call it), and it's very hard to communicate with people in game. I'm using Kik Messenger right now, but you can only communicate with 1 person directly. So what I'm looking for is an app that allows me to communicate with everyone in my alliance at the same time as well as 1 person directly.

If you have their numbers Viber is good.

VIBER BRO BANANA OUT

Skype instant messaging. Or group SMS on the imessage app or MMS app.

IPhones have a group messaging feature (everyone must have group messaging enabled for it to work, but they do not all have to have an iPhone). If they do not have group messaging, they would only get your messages and only reply to you.

There's an app (free) called We Chat that is great and I believe you can communicate to a group of people or a single person. You can text, send voice messages or pictures, etc.