@Mother1 This would be a brand new battle mode separate from 2vs2, with it's own daily and all time lb. The way in which I believe it should work is that players have the option to team up with 5 different partners from their friend list, if they want a new partner after this, they'd have to drop 1 of the previous 5 etc. The lb would show both players on it at the same time i.e.
Mother1 / Variation 90%. . For the top 5 the picture would be split in half with both players on it, or you could allow teams to choose a custom icon if that's too difficult to implement, basically what we have for flags.
Note: How the total wins would work it is intertwined with your selected partner. For example, on your char page it would be: 1vs1, 2vs2, jugg, 2vs2 (team) partner 1, 2, 3, 4, 5. It would make quite the list if 5 options, so it should possibly be cut down to 3. Or even charpages just showing your highest ranked team.
I'm not sure if it is in the FSI or not, however even if it is, it's quite evident that it's not going to get implemented unless a large amount of the community can show the devs that we really want this, I honestly believe that even though this game is inevitably dying this implementation would keep players happy even if we all know it could be a waste of time, at least players can say they actually had fun in Epicduel again, as at the moment for myself at least. This game's most important aspect (PVP) hasn't been enjoyable for a long time.