Pretty solid! I only have a few criticisms.
First off, the praise. I love the sound design! The whirs as you approach dashmode really add to the vibe you seem to be aiming for with Scarf as a character. I'm also a pretty big fan of his moveset in general. The Float Dash and Gravity Jump being arranged the way they are leads to a really unique flow between them that really adds to the feel of the gameplay. And, lastly, while I don't quite understand the decision to change the music out - as SRB2's existing soundtrack is probably my favorite of any Sonic game, official or not - your choices of music were all solid (with maybe the exception of Fang's theme, as STT16B's version is shorter than SRB2's and is generally a bit underwhelming for a full fight.)
My only real gripe is the animations. The spritework itself, while not quite as solid as the vanilla stuff, is still quite good and fits in pretty nicely. However, the slashing animation being constrained to just a vertical swing lessens the impact quite a bit - I'd recommend changing it to be more diagonal, but I understand that can be difficult to animate from some angles. Scarf's idle animation is also about the same as Sonic's animation, which detracts a bit from his personality. I'm also not personally a fan of the taunt he can do with the Toss Flag key - I don't know if it's an inside joke or anything, but I personally think it detracts from the personality of the character, which I think is the difference between poor and well-done executions of the concept.
Overall, as I stated before, this is a really good mod! My gripes aside, the flow and feel of Scarf's moveset more than make up for the few flaws the character has. He may well earn a spot among my favorite modded characters for SRB2!