The volume is inconsistent, so I had to max the volume to hear what was being said, so most may not know there is any sound after the first rap battle. You may want to try normalizing the audio in Audacity or decreasing the music volume or adding subtitles. All the characters sound the same. The spoky kids began sounding different but the you broke character in the middle. You also may want to animate the mouths so we know who is speaking, especially when more then one character is being introduced & no other animation is happening. You can also find voice actors in the newgrounds voice forum.
GF is shaded differently then the rest of the characters, which I think works & kind make her clothes look like sexy skin tight vinyl. You also had few good fluid animations like the spoky kid hand pointing at the girl.