i have no idea how it could be implemented, but i think it could unbalance the game unfairly. 2 decks against a false god would create a buddy system, or even worse a piggyback system, which i find displeasing.
the other idea in your title though is quite cool though: a 2v2 match would be really fun, and open up new synergies between decks. that would be fun!
by the way, this is your first post, so hello to you, and welcome to the forum! have fun!