Weakest Link is a name given to the common format for WPC team rounds. The name comes from the title for WPC 2003/Part XII, the first appearance of such type of round.
In the Weakest Link format, each member of the four-person teams is assigned their respective individual puzzles. They tend to differ per team members and the assignment of puzzles is part of the strategy. After each member completes their individual puzzle, a referee will check their solution. If correct, a fragment of the team puzzle will be revealed. Solvers who completed their individual puzzles can then work on the team puzzle, but it will not be fully revealed until all four members arrive at the team table.
In some Weakest Link rounds, cooperation on individual puzzles is allowed. A common rule for cooperation goes like this: A solver who completely solved their individual puzzles can choose either going to the team table or helping another team member who is struggling. There can be at most 2 persons at individual tables.
This format is very common in team playoff rounds.