I'd start by saying, forget for a moment that you're playing teams and focus on having a deck you like and are comfortable with. A less experienced player will do better with an average deck they know well than an amazing deck that they don't understand.
Now that you have an offense and defense, have your partner play the same offense and defense. Build them in a way that they work well together. Use characters that can band to one another's cards. Use Fortresses/Sites that benefit one another. Use cards that benefit from the number of a certain card type that's in play (like Susanna).