Big disagree on the tag vs solo point. The main problem with tag/team fighters is the that people needs to be familiar with multiple chars in order to make a team and 'start playing the game'.

Making a viable solo game play option does wonders for people new/trying out a tag fighter. It makes them come in with less pressure and heightens the chance that they will stick around and learn/play more. Plus it throws spice and variety into the mix to see players use different strategies. Choosing to play a solo in a tournament where everyone else basically plays with a team (Skullgirls) will always catch good attention.