this was good, with the proper use of sprites+animation+good use of backgrounds, thus building up to be a good animation, but the story is.... well-known.
sonic+super mario+DBZ+mechas? come on, whats next? super-naruto-man, along with bleach and megaman, following the trail of sonic in the battle for the delta halo?
come on, man. you have skills, thats certain, and your animation is good, and it also has subtitles, with is a huge plus, and it has a nice intro/design/animation going on, while all the sprites are used perfectly in the movie, but still, your problem is the story.
while the megaman+sonic universe is quite more original than alvin earthworks ''sonic+mario+SBZ'' old recipe, it stills needs to stand out of the crown a bit more.
make a NEW story, with maybe sonic doing something other than helping super-mario's princess.
dunno, make sonic going on an epic adventure in the future, to save, lets say his future-self from his enemy, shadow, or something, and he teams up with rouge to talk some sense into future-shadow.
or, you could make something even more different, and plan a movie that has a futuristic enviroment, and it shows how sonic's world has changed since aliens arrived in mobius and rebuilded the planet like a modern day atlantis, thus defeating eggman at his own game.
there are many ideas, but the combination of mario+sonic+DBZ isnt new or freash anymore.
i hope i am not rude or harsh to you, i just see that you have the talent, you have the SKILLS in sprite animation, and thats great, you also added subtitles which is a big step forward in a movie, and its bad to see that the only part of the movie that you seem to have trouble with, is teh plot/originality.
that is all, take ir or leave it, that is my advice. try a new approach in this. you have the skills, so you can do epic stuff.
either way, you can do good(visually) movies.