Use 'team up' when different groups or individuals combine efforts for a shared purpose or project. Small businesses might team up to compete with larger companies.
Pro Tip 2/3
Short-term Pairing
'Team up' often implies a temporary partnership, not necessarily a long-term commitment. For the science fair, we'll team up, but work independently afterwards.
Pro Tip 3/3
Active Participation
'Team up' suggests active and equal participation from all members to achieve the goal. Each department will need to team up and provide inputs for the merger.