Yo, I saw that you didn't get the connections for Cloud vs Zero, and I figured I might as well tell you, as you posted it on Dumb Matchups discussion thread, and said you didn't know the connections.
Anyways, here I go.
Cloud and Zero are both blonde-haired swordsman who are soldiers that are a creation of science (Cloud by Professor Hojo's Mako experiment and Zero by Dr. Wily). Both suffer from amnesia about their pasts due to the result of memory tampering and experience of traumatic events, this often led them to questioning their existence and purpose, but never allowing their own past to defined who they are nor did it stop them from doing what is right.
During their time as a Shinra soldier and Marverick Hunter, they never had friends, always depended on no one, but themselves until they met the likes of Zack, Aerith, X, Iris, Axel, and the rest of the Maverick Hunter team. That's when they finally knew what it was like to find a family and for them feel a personal sense of responsibility and guilt for being unable save them.
Aerith and Iris are also two of the most important women in their life that they loved and cared for and their deaths deeply affected them psychologically, it changed who they were as an individual.
Leading to them becoming a beaten and broken wandering warrior, soldier, and swordsman without a purpose--- however in due time eventually they found a new family, a new purpose, and someone worth dying for (Tifa and the orphans of Midgar for Cloud and Ciel and the Resistance for Zero) and thus becoming humanity's greatest protector and guardian.
They are also the successors of their greatest nemesis, Sephiroth and Sigma who were once celebrated war heroes and they ended up becoming a far greater hero then they could ever hope to be..
So yeah, those are the main connections for the MU.