The Usos (C) vs The Bar vs The Hardy Boyz vs The New Day (for the SmackDown Tag-Team Championships)
The Usos will definitely be defending their titles in a multi-man match and I think their most likely opponents are The Bar, The Hardys and Woods and Big E.
PREDICTION: Xavier Woods and Big E
The Revival (C) vs Aleister Black and Ricochet (for the RAW Tag-Team Championships)
I wasn't too sure about this one and whether it will be even on the Mania card. I think there's a good chance Black and Ricochet challenge The Revival if the RAW Tag-Team Titles are on the card.
PREDICTION: Aleister Black and Ricochet
Samoa Joe vs Rey Mysterio vs Andrade (for the WWE United States Championship)
While I'm sure this match will be great considering the talents involved, Joe will not be losing the title.
PREDICTION: Samoa Joe retains
Roman Reigns and Dean Ambrose vs Drew McIntyre and Baron Corbin
I initially thought that WWE might do Reigns vs Ambrose but after RAW last week, this seems more like. It will also be a good send off for Dean Ambrose if he is actually leaving.
PREDICTIONS: Reigns and Ambrose win