Five collaborations, five very different products, one thing in common. It is not the marketing.
Every one of them started with a licence agreement signed before anything was designed. Two brands cannot share a product without each granting the other permission to use its registered marks, and the terms of that permission decide who profits and who carries the risk.
What the agreement has to answer
Which marks are licensed, and in which classes. Which territories. Whether the licence is exclusive. How long it lasts and what happens to unsold stock afterwards. Who approves the artwork. Who owns any new design created for the collaboration. Who pursues counterfeiters, and who pays for it. What happens if one brand is later involved in a scandal.
Where these deals fail
Almost always on ownership of what is created jointly, and on what happens at the end. If the agreement is silent, both parties believe they own the new design and neither can use it without a fight.
Before you say yes to a collaboration
Confirm your own mark is registered in the relevant classes. You cannot licence what you do not own, and a partner lawyer will ask for the registration number. In Mexico a licence can also be recorded before IMPI, which makes it enforceable against third parties.