So I played the beta-access of Splatoon and enjoyed it but am curious about the co-op. I like to play Wii U games with my girlfriend and while normally I don't think this game would interest her (she's not great with anything dual joystick) the motion controls might make it easier for her. So my question is can you play couch co-op online and if you can how does that work with motion controls since you would use the Wii U gamepad and there's only one. Thanks a lot for reading.

Unfortunately there isn't a way to play two local players online, it only allows one per console. There is a 1v1 local multplayer mode that is fun but not the main draw. You can both play with motion controls with one person on gamepad and the other on the Pro controller with a wiimote strapped to it(official Nintendo advice).