What is the most important aspect of a TEAM?

In addition to the great answers above I would like to add BALANCE.
The balance of a team is vital for managers to maximise best performance.
Balance strenght and weakness and ensure that the team is happy to support each other.

the most important aspect of any team
1- communication 2-support and cooperation 3-skills 4-the right attitude

Trust - team members need to trust each other Common goal - team member need to have a common goal that they can rally behind Natural authority - managers know what they can do best and recognize what their team members can do best and each respects each other's "natural authority" Sense of satisfaction - team needs to feel proud of they produce, if they are forced to produce stuff they are not proud of, their morale will be way down

Common goal If the whole team have the same goal, it will make them work side by side to achieve, which will boost their productivity to the max

For me the most important aspect of a TEAM is being 'TOGETHER'.
This means that they are ONE to achieve any common goal or objective.