What are the implications of this, what if they teamed up
Two different generations, really.
Santa Anna was born in 1794; he was 27 when Napoleon died (1821), and 21 when N was sent into (permanent) exile.
Iturbide (born 1783) was more of a contemporary of N, and actually lived longer; he was executed in 1824.
Santa Anna (at least publicly) declared for the Liberals against NIII and Maximillian, but Juarez wanted nothing to do with him; he died in 1874.
Best,