Pixel Art Team Composition

My team is starting to do some contracting of pixel artists and I think it would be wise to tap the forum's knowledge before getting too far.

The basic question is, on successful teams with multiple pixel artists, how were those teams composed? Was there one person doing sprites, another animation, and yet a third doing concepting and direction? Is it unrealistic to get an artist that could do all of those things? Are the roles any different than those you'd see on a game with other forms of 2D art?

I'd love to hear from people who have been on successful and even unsuccessful teams, if you're willing to share.