The teamwork tag has no usage guidance or tag wiki, but it's currently being used on 11 questions about a variety of systems:
- 4 of them are tagged as being about Fate Core
- 1 is tagged for Fate and the Dresden Files RPG
- 1 is generically tagged as science fiction and GM techniques
- 1 is tagged as Shadowrun 5th edition
- 1 is more broadly tagged as Shadowrun
- 1 is tagged as D&D 3.5e
- and 2 are tagged as Pathfinder
"Teamwork" seems to be the name of a specific concept in Fate, and the name of a feat in Pathfinder. However, these are different things, and the term "teamwork" is also generic enough that it's getting used to refer to working with other players or characters in any capacity.
Two other tags that relate to inter-party dynamics and working with other characters are helping, whose tag wiki says it refers to:
mechanics whereby one character can help (aid, assist) another and grant the recipient some sort of mechanical benefit
...and party, whose usage guidance says it's for:
questions about composition or interplay of a character party in-game
The teamwork tag seems to be getting used interchangeably with both of these concepts.