UMVC3 Trollguide

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Disclaimer:
This is a troll guide that you should not take seriously. I'm the worst player in the world and UMVC3 is the best game ever made with incredible mindgames, spacing and tactics. My guide is full of shitty advice that will not help you win at all, so don't even bother wasting your time reading it.
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And now for the guide:
MVC3 is what they call in Japan a Kusoge.
http://vimeo.com/33999894
As such, it's not a complicated game, and that has not changed in Ultimate.
A point character in Mahvel 3 is judged by 5 criteria which will be mentioned in the order of importance:

1. You may call this 'mobility' but it's something more specific- An effective method to get your downward approach. (Examples: Wesker/Zero/Dorm/Dante teleport above+behind you and attack with a jump-in, Magneto/Storm Tri-Jump, Doom/Wolverine/Trish divekicks, Spencer zipline above you etc.)
2. Getting good damage from the moves that are easiest to hit with. (Example: What is Doom's biggest buff from MVC3 to UMVC3? Getting a full combo from the divekick.)
3. A ground attack that has good range+speed+priority. For the times both of you press buttons on the ground and you want to be the one winning that scenario. (Wesker's 2B, Trish and Phoenix's slides, Zero's everythinglol etc.)
4. A fast, reliable way to punish assists regardless of the position you happen to be in. (Think Shinkuu Hadouken, Chaotic Flame, Bionic Arm, Magnetic Shockwave etc.)
5. Health.

These 5 criteria, considering the order of importance, explain the dominance of certain characters.
Wesker has a great 1,2,3 and 5.
Dorm has 1,2,4 and 5.
Spencer has 1,2,4 and 5.
Zero has multiple 1s,great 2, the best 3 and even a potential 4 with his lvl 3 super.
Viewtiful Joe has nothing. lolol

2,3,4,5 should be easy to understand for anyone who played this game.
Let's talk about #1, because to play this game well it's crucial to understand its (simplistic) neutral game.

Upward attack vectors don't exist in this game, and even in specific cases when they do exist, they are not reliable. They don't have good priority, don't lead to good damage and are risky to attempt. (And even the assists suck at this. R.I.P. Captain Commando.)
http://i41.tinypic.com/21109kz.png

Which is why downward attack vectors DOMINATE. They have the priority, damage(start TOD combos), and relative safety for the lack of real counters. (Which is why MastaCJ doesn't care about puny voomerangs.)
http://i41.tinypic.com/2803wj5.png

So the whole neutral game is basically consisted of you getting above your opponent and attacking downwards.
http://www.youtube.com/watch?v=2AuybZx4vmE#t=2m17s
The only real solution to this situation, is to avoid being in that position where you are UNDER someone.
This is where the assists come into play. Their main job is you get you stuck on the ground and prevent you from moving away while the opponent gets into a position above you, or even BEHIND you, creating a mixup situation.
You probably know the characters you use way better than I do, so take this general insight on the game and think how to apply this for your team. Once you do, you'll start seeing better results.