If Cersei had married Rhaegar instead of Elia, how would Robert’s rebellion have played out? Would the Lannisters Tyrells and Targaryens have been able to win the war?

Interesting, haven’t thought of that scenario.

However, I don’t see Tywin reacting to Rhaegar dishonoring his daughter and Aerys holding his daughter and his grandchildren hostage with fighting on his behalf, given how he reacted to Aerys holding Jaime hostage in OTL.