The idea could work, but it is a very ambitious idea, and as such, I could see it collapsing quite easily- that's not to say you can't handle it, I'm sure you can, but given the scope of the idea it seems as if it would need quite a bit of careful moderation to make it work out. Still, I love the Warriors series (and crossovers), and I know a have a good deal of knowledge about most of the series you listed, so I'd love to help in any way that I can.
I call it mainstream because the next in line that I heard off in my popularity listing is SAO, and I've included it (though only Aincrad) Besides, SAO is kinda new... Because of the anime. The LN started in 2008, I think? Others don't have anything to do with fighting.
I'm working on the concepts so that it doesn't blow up in everyone's faces. Highest stat wise in the worlds I have is Madoka Magica, and that's because the girls there actually use their souls to do magic. Next is Nanoha, but in canon the characters there are Double Letters in rank. OCs should have lower ranks.
Each have their strengths and weaknesses, like how Suikoden characters have the highest Leadership skills with low defense and health, while Grand Chase characters have great Physical skills with mediocre Leadership. In all honesty, Avatar characters are the most balanced, leaning towards being weak as they don't have magic. I didn't include DB because Avatar characters can take their place, with + points as they can bend elements.