A 7, with mercy.
Not bad for a first flash. Me and a friend of mine are actually working on a flash, keep an eye out for something around the name of "Kingdom Sprites" (that's the title for now) by Silencer169 in the upcoming months. The one things that kept me from giving you a 5 and instead giving you a 4 on the main rating scale is that knuckles turns into mechasonic... now it would have made more sense if knuckles had actually summoned mechasonic or if you had used Super Knuckles from Sonic 2 and so on... but oh well, never the less, a decent flash :) Good job.