Gen Rex: “Hi, I'm Rex Salzar also known as Generator Rex or Gen Rex.” Ben 10: “Hi, my Name is Ben Tennyson. Wait Rex is that you? It’s been a long time since we have last seen each other.” Gen Rex: “Yeah, Ben? Ben Tennyson. Is that a new watch that still allows you to turn into those weird Alien things?” Ben 10: “Yes, it’s the Completed Omnitrix just so you know.” (If you want to know how they met each other watch the Generator Rex heroes United movie)