Ehhh...
Sonic: ok
Star Wars: Fantastic
These are both great franchises, however, the idea to combine the two is just wrong. Sonic just does not fit in with Jedi's and Stormtroppers... It's like making Jim Carrey the star of Die Hard or making Carlos Mencia do stand up.
If you must do this, then please i beg you, make the storyline acceptable, put alot of thought into the plot, don't just randomly slap characters into the fray and add random fart jokes only to expect perfection.
Take your time, and be sure to review your scenes carefully friend, when your doing this kinda stuff, the slightest goof up can easily spoil your reputation. I'm praying you'll do well man, good luck.