Ben 10 (2016) S0503 Alien X-Tinction The Final Battle (FanMade Transformation)

With a newfound attitude, Team Tennyson busts out of the cave entrance and makes their stand against Alien X. They fight against him, protecting their teammates when in danger and pressuring Alien X to focus on defending against attacks from all directions. Eventually Gwen 10, as Ripjaws, pulls Ben's Omnitrix out of Alien X's chest, and Ben finally takes it back. He turns into Heatblast and teams up with Original Series Ben, also as Heatblast. The team regroups and attacks Alien X, pulling off as many Omnitrixes as they can before he pushes them away. Eventually, he is left with only one Omnitrix left, and he stands off against Ben, as Four Arms. The two run at each other, and Four Arms triumphs in the clash with his "Quadruple-Decker Knuckle Sandwich", finally defeating Alien X. Alien X laments that he was "so close", to which Ben says he never stood a chance because he was trying to do it all on his own. Alien X then detransforms, revealing he was also an alternate version of Ben this entire time.