Tenkai Knights

Eons ago, a cube–like peaceful planet named Quarton, populated by shape–shifting living bricks called Tenkai, was ravaged by a war between two opposite factions: the Corekai and the Corrupted led by the ruthless warlord Vilius who desired to obtain the source of Tenkai Energy for his own purposes. However, the only ones who were strong enough to defeat him were the Tenkai Knights: Bravenwolf, Tributon, Valorn and Lydendor. Facing defeat, Vilius unleashed the mighty Tenkai Dragon, who was later defeated by the four Knights and its fragments were scattered across the planet. These heroes were never seen again, but the Corrupted have returned more powerful than ever. Now on planet Earth in the year 2034, four teenage humans named Guren, Ceylan, Toxsa, and Chooki find an interdimensional portal to Quarton where they are chosen by the Guardians to become the new generation of Tenkai Knights and prevent Vilius to take control of both worlds. (Source: Wikipedia)

Zoids

Zoids are beast-like fighting machines used in both everyday use such as transportation, and special use such as war. Some types of Zoids, know as Organoids, are miniature Zoids that are living organisms. These Organoids have the capability to fuse with a non-living Zoid and make it much more powerful. Van (Ban) Freiheit discovers a Zoid Organoid in an abandoned laboratory while running from two strangers piloting Zoids. Also in the laboratory, in an animated suspension tube is a strange girl. He breaks the tube open and takes her and the Organoid with him. Spotting a ruined Shield Liger Zoid outside nearby, the Organoid fuses with it and repairs the damages. Making his escape, Van names the Organoid Zeke, and decides to keep him as a friend. The girl, who says her name is Fiona, wants to find something called Zoids Eve, and so Van, Zeke, and Fiona begin their adventure. (Source: AniDB)