What are the minimum requirements for a team?

A team of 2 is a must, preferably when there is at least one person that can check the other's work. A strong majority of the candidates we interview mention they would like to work in a team, regardless of their experience. 'One man army' projects are not optimal for developers. It’s hard to motivate people with such projects; the risk is too high, and the fun-factor too low. We want our people to work in a future proof way, which is why we do not consider such opportunities.