First of all, I'm just going to flat out say it, but your story is awful. I'm sorry, but it is. But before you hit 'ban,' let me get to the real reason why I'm posting. I, like you, am a fan fiction writer. This isn't any sort of self advertising bull (because I hate people like that, but I may inadvertently do it,) I made the same mistakes as you did (and I'm still guilty of it today,) but get every chapter proof-read by someone else (like me, for example,) before you post it online. I can give you some tips for now, but no more until someone responds.
-When doing a crossover, try to stick to two stories. It keeps the story in order and doesn't lose your readers in the text. Doing three or more stories in a crossover is a bit tricky, and you have to know what you're doing. Otherwise, you get all the trolls on your tail.
-Like I said, get this proof-read before you post it. And use spell check.
-Check your tenses! There are past tenses (like 'I did this') and present tenses (like 'I am doing this')
If you want to quickly contact me, you can contact me via deviantart (which is Blockhed13 as well) or fanfiction(dot)net and look up Blockhed13
Keep following your passion, and don't let any stupid trolls get in your way. Keep writing!