Zoids: Fuzors(2004)

Zoids: Fuzors is an anime series following R.D., a delivery driver for Mach Storm, a company that doubles as a competitive Zoid battling team. Obsessed with finding the legendary Alpha Zoid—a machine his father once told him about—R.D. works tirelessly to fund his search. During his first Coliseum battle, he faces an opponent whose Zoids can fuse together, sparking a revelation: his own Zoid, Liger Zero, possesses the same fusion capability. This discovery sets R.D. on a larger quest to uncover the truth behind the Alpha Zoid and prove his father's claims. As he battles through the Coliseum ranks, R.D. must master his Zoid's unique abilities while navigating the competitive world of mechanical beast warfare.