Power Rangers Time Force: The End Of Time (2001)

Jen, Katie, Lucas and Trip receive a panicked call from Alex. Frax, he warns, is building Doomtron, a super-robot that will destroy the city. If the teens don't return to the future (3000) now, the won't survive. Wes, however, must stay in his own era-2001-so the teens stay and help him fight.