Cosmo Clock 21
Banned
Short answer: no.
Long answer: nooooooooo.
Even longer answer: No, at some point you are forced to rely on leader abilities such as 2x attack for all monsters of type x, which will force you to run a 1-3 colour-team to be most efficient.
I disagree; this team's gotten me all the way to Tomb of the Saint Expert and Castle of Satan in the Abyss:
I'll probably sub in Angel once she evolves to Archangel. What's important isn't that I'm running four colors, but that each team member (asides from the dubmythlit lol) plays some kind of important role in the team.
Once we get the Egyptian God update, four color teams become mandatory due to Horus' leader skill, but that's another bridge to cross.