Also, one of the agents at the secret base in the first movie must have survived Salt's onslaught. He sent a message to other sleeper agents everywhere of Salt's betrayal. The Rival sees this as an opportunity to fight her in an ultimate showdown. During the fight, just when she beats Salt she'll hit her Berserk Button (Mike's death), which will be her own downfall.
Why can she jump onto cars, survive ridiculous falls, and beat the shit out of everyone? Because the Russians didn't just train their minds, they also modified their bodies.