I need some help badly

I will say this is my first post even though I have been playing MvC3 since vanilla. I have been practicing and practicing I feel like iv’e hit a complete wall. I’m frustrated to say the least when i’m not getting bodied I drop combos due to lag. I don’t know where to go from here, My problem might be the fact that I can’t get new teams in and my first character was She-Hulk. I feel like if I don’t use her on a team ill just get bodied even worst than when I do and for the most part that is true. Ever time I replace her with someone else I get destroyed, and as soon as I put her back on my team I beat someone because of her, yet I know she is a weak character and her weakness will get highlighted in a match and I will get wrecked. aside from she-hulk I have Taskmaster he was my most recent attempt to get rid of She-hulk (I tried Task, Dorm, Deadpool) and I failed so bad. I have alot of matches with dorm and dead so i’m stuck in the same loop as I am with she hulk. I want to build a Team around Taskmaster but of my current team (Task,She-hulk,Dead) he is my weakest character. I can’t get in all people do online is jump (which I don’t how to convert a hit to a combo in air with task). Also My BnB with task has some picky timing mainly on the part with the shield skills and launcher and again at the end of his jf.H trying to convert into j.M they will drop out online due to lag but in the lab I get it every time. My BnB with is is c.L c.M s.H b.H (delay) S j.M f.H Arrows M land Shields Skills (delay) S j.M j.M j.H f.H j.M j.M j.S (Land) P2 (Deadpool Katana-Rama) arrows L Legion arrows L+M. From there I can always DHC into shehulk and then do one of her various resets coming after the hyper combo. It is vary effective when it works. and If I lose those two I just use deadpool’s X-factor infinite to level the game, win, or they will wreck me and ill lose while deadpool is glowing red. I need Taskmaster Tips, ways to get in synergy and most importantly a mentor. I see people online with over 1000 L’s and wonder how have they not broken there disk yet? Also I need alot of tips to adjust from offline to online speed.

If you need help with taskmaster, i can tell you pretty much everything you need to know; match ups, synergy, combos/hitconfirms ect.