Why is Best Ending the only category? Normal is easier and does count as a legitimate ending, doesn't it? At least compared to the "leaving the island with Kazuma" ending.

Can someone explain this to me?

Shouldn't there be a category for unlocking and defeating the extra boss (as in main game, and then the extra boss stuff)? It's not all islands, but I feel like it should be an existing category.

I'm not sure if that would work very well. In the case of Sonic Advance 1 and 2, you can start from the first stage and then it acts like a classic sonic game, sending you thru the levels till the end. In Sonic Rush, you would have to select each level separately on a completed save. I'm not sure that would work.