Wow...
*cough* Super Mario Bros. Z ripoff *cough*
To be serious this wasn't all that good.
The dialogue was poorly written in some parts with some inconsistencies such as Mario calling Peach, Princess, then calling her Peach which causes the dialogue to become ugly and bizarre.
Poor dialogue.
Then out of character moments along with the plot. First I just want to get out of the way that SMBZ does have a ridiculous plot but at least it made some sense...
First, Shadow building a transmitter?
Not only is that way out of character considering he doesn't even fiddle with machines but that he built it a day before getting the transmission from Mario?
Well, what luck...
Another thing, Mario had a transmitter too? What are Mario and sonic buddies?
Argh, there's too much stupidity in this plot to make any sense of it.
Plus why the hell did you just invert Bowser's sprites? Were you that lazy? You could of at least done a bit of editing, Christ.
In short, bad dialogue, bad plot and lazy sprite work.