Ben 10 Ultimate Alien S3 Ep 6 - F2F Transformations

Season 3 Episode 6 The Perfect Girlfriend
Ben goes to Julie's house and meets her father, who says she isn't home, and that Ben should know. Ben then finds her at his place and gets her to watch with him a tennis match on TV. However, he finds it to be a replay of one of Julie's matches from yesterday. He finally recognizes the girl he is with must be an imposter and she reveals herself to be Elena Valadis, who had disguised herself as Julie using the Microchips. She explains that since Ben loves Julie, she masqueraded as her and tried to provide Ben with everything he wanted to make him happy and then shape-shifted into other four unknown women if he does not like them.