Zatch Bell! Attack of Mechavulcan (2005)

Original title: 金色のガッシュベル!! メカバルカンの来襲

As Kiyomaro races to catch the bus to seaside camp, little does he know that Dr. M2, a demonic magic scientist from the future, has sent out a robot to kidnap him. He's trapped in limbo with the mad magic scientist who wants to be his partner and an army of Vulcan robot lookalikes. Dr. M2 sends a robot to pretend to befriend Gash, keeping him away from Kiyomaro until M2 can abscond with the teen genius to the future. In the end, it comes down to saving the world with a little help from their friends...