I would wish the tag online, but overall because I like the mode and to play it also just against the CPU (and in addition in Doa5 this give the possibility to play with real people online, a game experience more near to Doa3.1 for who interested in it).
Personally I think that play in tag online with another player it's not a thing so easy and simple: yes, it's not needed the ability in the execution of the tag character's moves, but surely you have to know however a basic knowledge of the other character, and in addition the tag juggles existing with him and also like your partner player act to know exactly what he desire to do before of the adversaries. Finally, in all this I think that the timing become an element still more fundamental that when the game is played 1 chara vs 1 chara and/or with just 1 person against another.
To think just that it's necessary to know the launchers of the other player to know when intervene (like seemed you were implying, if I'm wrong sorry), seems to me a reasoning too much simplicistic.
However like I said, my answer to the poll is a big "YES!" XD And off course I find funny to create a team of 2 different people to play online me too.