The story begins when a mysterious rift opens in Manhattan, through which (in his Ultimate Alien form) is transported into Rex Salazar’s world. Mistaking one another for enemies—Ben seeing Rex as an alien and Rex seeing Ben as an "EVO"—the two engage in an initial battle before realizing they share a common foe: Alpha .
As of 2025–2026, the special is not consistently available on all streaming platforms due to licensing shifts. It was previously on HBO Max (now Max) but may have been rotated out. Digital purchase (Amazon, YouTube, Apple TV) remains the most reliable legal source with official subtitles. Ben 10 Generator Rex Heroes United English Subtitles
You're telling me you fight monsters with that thing on your wrist? The story begins when a mysterious rift opens
00:01:15,000 --> 00:01:18,200 [SFX: WORMHOLE RUMBLING] [ALARM BLARING] It was previously on HBO Max (now Max)
A lake in the park is shaped exactly like the Ultimatrix symbol.