Ben Tennyson falls through a wormhole and encounters Rex. The two heroes must unite against a foe that can absorb their powers.
| Actor | Role |
|---|---|
 Daryl SabaraRex Salazar (voice) | Rex Salazar (voice) |
 Yuri LowenthalBen Tennyson/Upgrade (voice) | Ben Tennyson/Upgrade (voice) |
 Wally KurthAgent Six (voice) | Agent Six (voice) |
 Grey DeLisleDr. Holiday (voice) | Dr. Holiday (voice) |
 John DiMaggioBobo Haha/Rath (voice) | Bobo Haha/Rath (voice) |
 J.K. SimmonsWhite Knight (voice) | White Knight (voice) |
 Michael EmersonAlpha Nanite (voice) | Alpha Nanite (voice) |
 Jennifer HaleBlack Knight (voice) | Black Knight (voice) |
 Freddy RodríguezCeaser Salazar (voice) | Ceaser Salazar (voice) |
 Dee Bradley BakerHumungosaur/Diamondhead/Lodestar/Big Chill/Upchuck (voice) | Humungosaur/Diamondhead/Lodestar/Big Chill/Upchuck (voice) |
 David KayeShocksquatch (voice) | Shocksquatch (voice) |