It's not much at all
I'm sorry dude, but this was just not enjoyable at all. I think its main fault was that there was no way to advance at the time you wanted. Most submissions that use dialogue boxes give you the option of being able to move whenever you want. Even the text in the dialogue boxes didn't seem to be much. It was weird to see Mario at first because of, well the title. This was also too short and it seemed to end randomly.
I have no idea why Cell randomly appeared. It reminded me of "Super Mario Crossover", but then again, I guess anything like this would resemble that. It's only saving grace was that the backgrounds were pretty good. You need to put in more action to make it more enjoyable. There just didn't seem to be a reason for the characters to be doing this.