First thing you need to do is find a partner to make a team with you!
I'd suggest posting a thread in the OoC Subboard asking anyone if they'd be interested!

Once you find your partner make sure a mod knows you're making a co-op team, and when they approve of it one of you may roll for a partner Pokemon.

This is different from doing a solo team as you must wait to roll for a partner until completing the Starting Team Mission, but for co-ops you roll for the partner first.

To complete missions with your partner you must keep in mind that there is still a floor requirement you have to meet. Each of your posts must be 500 words minimum.
One post from each of you counts as half a floor.
Two posts from each of you counts as a whole floor.
So for a four floor dungeon you must make a total of: 8 posts, four posts each. 500 words minimum.*

OR one of you can do the mission normally and have someone else roll for the partner when it is completed!

This is actually a bit longer than if you were doing a team on your own, but there are two of you working on this together and so it balances out!

Co-op teams do not fall in the 'one mission at a time' rule!
You may do a mission on your own at the same time as a co-op mission. Co-op missions have their own cool down period on a per-team basis.
Co-op missions are also granted an innate extension, making the time limit 45 days instead of the normal 30.

Note that while you can take as many co-op missions as you have teams, if we feel that you only needed an extension due to taking too many missions your rewards may be reduced. Please only take as many missions as you can handle, both out of consideration for the moderators, your partner and your fellow guild members.

*These rules are currently under observation. Please endeavour to meet the above requirements but considerations will be made should they fail to be met.