Megas XLR, on Cartoon Network
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This series is based on a short which was originally called "LowBrow." The first and only episode of LowBrow, "Test Drive," was extended to become a half-hour pilot for Megas XLR. Both the original short and the new series are pretty cool, totally anime-inspired. It's about a a giant robot from the future (MEGAS), which is humanity's last hope in the war against alien invaders called the Glorft. Actually, it turns out to be a prototype mech the Earth forces had stolen from the Glorft, to send back in time two years to help them win a battle they originally lost. Unfortunately, the robot ends up a lot farther in the past than intended, in present day New Jersey, where it's found by this guy named Coop, who modified it by putting a car on the head and making it drive like a video game. Or whatever. When he's showing it to his friend Jamie, this woman named Kiva shows up from the future to reclaim Megas. But then the Glorft show up to reclaim it themselves. Coop pilots Megas in a kick-ass battle against the Glorft, who then escape into nullspace, so they can return to fight again.
It's all pretty funny and cool and has some voice actors familiar to anime fans. Plus it's from the creators of the MTV cartoon Downtown, which was also cool. There's also a character named Goat I think is the same "Goat" from Downtown. Anyway, there are occasionally battles between Megas and the Glorft, but there are plenty of other battles, too. Not sure what else to tell you, except of course that Kiva is not at all happy that she's stuck in the past, having to deal with Coop and Jamie all the time.... And the theme song is wicked awesome.