After taking a first look at Natalya who seems to be really powerful, I think every faction should get a totally unbalanced, overpowered Epic character. That would not only even the board, but you could also agree before playing to play "epic mode" (Teams may include Epic characters) or "normal mode" (without Epic characters). That way, each faction would get a new and really mighty character to fight against those other unbalanced characters.
Furthermore, I think those Epics should be powerful beings like demons, mythological creatures like Asteros or important, charismatic faction leaders - not obscure mechanics in powersuits!