not bad
pretty good.
animation- really good overall, could be better in some parts. i hated when knuckles was making all those movements, it just looked really wierd, if you want motions like that, i suggest hand drawing it, it turns out much better.
plot-... well, like every mario/sonic character fight, the sonic character, in this case knuckles, gets a mario world item, that wouldnt be bad, if every time it happened it didntturn them into ab uber form that completely dominates the other person
sprites- well, im talking about ice knuckles, the sprites were very inconsistent, some parts he was glowing (which i didnt like, because the glow wasnt that good) and others he was just blue, so that was very confusing.