Previously in Tekken 6 : Bloodline Rebellion and Tekken Tag 2 [pre-Unlimited version], lifebars were set to 180 damage points for both games. However, now that Solo / single character mode has been added to TTT2 : Unlimited, this has changed.
Samechan from Japan has done some damage testing with the game. Unfortunately, I am not able to translate everything completely, but the basic gist of it is that when using a Tag team, you have a lifebar of 165 damage points for each team mate. Solo, on the other hand, has a lifebar of 180 damage points. While this may not seem like a big difference, things to remember is that Solo deals more damage than a Team. Solo mode also is in constant regeneration of their lifebar.
It seems that Solo does roughly about 20-30% more damage than a Team does… this does all seem like a considerable amount, but we’ll see how it all pans out when the game gets released. Of course, a lot of this could all be changed / re-balanced upon or post release, so nothing is finalized yet.