You can't make really any assumption on the tiers really. The trailers are choreographed to make them look OP at times and others bad. As well the mechanics are new and old specials and normals have new properties. Their simply too much to factor. You might guess a good point character, but the assist mix could blow that theory away.
All i know is there is a TON of diversity and we'll see a lot more flavor to the battles. I'm gonna be using keep away and projectile characters like the whore I am so my favorites are resting on:
M.O.D.O.K, Trish, Zero, Dormammu, Ameterasu, Arthur, Super Skrull, Spencer
I can almost guarantee Arthur will be one of my team.