Right, the game just says "Win a Tag Team Championship match in a Rivalry with a custom Superstar", and I've tried several permutations of this. I've had a tag team of existing Superstars win the WCW Tag Team belts from a team with a Created Superstar (that they were in a rivalry with) on it, I've created a team with two CAWs and had them win the belts from an existing team of in game superstars after setting up the rivalry.....NOTHING has worked.
So, I ask you all: how do I unlock the NXT Tag Team Championships?
I think it only works if you let the rivalry run its course without editing matches. I set up a medium length rivalry with Team 3D (champs) vs Wyatt Family for a created tag belt. Played or simmed every match (some were singles matches) and on the last week (or PPV - I forgot which) there was a tornado ladder match for the titles. I won with the challengers and unlocked both NXT and classic WCW tag belts
When there is no more room in Hell, the Dead will walk the Earth...