Watch the tournament on YouTube on SiIvaNugger:
The tournament is no longer operational on Scratch, but you can submit here still.
If you want to make your own arrangements, the thumbnails are in the Beneath Area 51 project.
The description is too long now, so check the Scratch Rippers Wiki for the character's sources.
Note: All contestants and assist trophies have been decided, so please do not suggest any more.