UPDATE: I have no plans to add any further contributions to this mod, as it's been 2 years since it was first released. I might come back to a Sonic in Mario Sunshine idea but it won't be on this project.
Yes guys, the legend that if you got all of the 120 shines and then got the book from the bottle which would tell you the secrets of unlocking this was true. You can play as Sonic the Hedgehog in Super Mario Sunshine!
With the hack, a digital version of the game, the root, and GCRebuilder...
The Playable version features some changes to the textures in the game to match with Sonic being the playable character, and Shadow will also be featured as the replacement for Shadow Mario (come on, it was asking for it!).
The Ill Piantissimo version will basically be the same as the regular game, except that Sonic will be replacing Ill Piantissimo.
Both versions will have text changed to fit with Sonic being in the game, as seen in the Ill Piantissimo screenshot above.
Do note though, that the text changes for Sonic hack will have text be directed at characters. So it might be odd if you replaced Mario with Rayman or something and had Sonic call them "mustachio."
Here is some questions you might or might not have but I will answer anyways:
"Will there be any level imports?"
While there are a few ideas I have for level imports, don't get your hopes up about them.
Even then, I'm not planning to add in many level imports, it will mainly just be for broken secret levels like Pachinko or Poison Lake. This is just Sonic in Mario Sunshine, nothing more, nothing less.
"Will there be any new cutscenes for this hack?"
Not exactly, that would require to animating 'n such. Plus, I've heard that cutscenes with mods can crash your game. So even if I did, it would probably be useless in the long run.