If you're looking for manga similar to Tekkon!! Zoids Kakutougi, you might like these titles.
In this world there are mysterious machines called "Tremble." No one knows where they came and why they were built. The only thing known is that they continue to evolve and attack humans. The only way to defend yourself is to try to destroy them, but there are those who have learned to control certain and use them to your advantage ... the Breeder. These extraordinary individuals, however, have a difficult life, always on the run from people who fear them and treats them as criminals. But Ion is not one to be discouraged, so he decided to follow his father's footsteps and become a Breeder, a tamer of Tremble!
Dr. Kaneda was developing experimental giant robot warriors to fight the allies during the Second World War, but before his creations could see action, Allied bombs destroyed the facility and killed him. A decade later criminals discovered two of the surviving prototypes, #26 and 27 in the series, and used the remote controlled robots to commit a number of crimes. Young Shotaro Kaneda, the twelve year old son of Dr. Kaneda, did some investigating and discovered that the mob were hunting for the twenty-eighth robot in the series, rumoured to be the most powerful of them all. Racing the villains, Shotaro discovers the robot first, along with Dr. Shikishima, a colleague of his father who was also believed to be killed by the Allied bombing. Together the two prevent Tetsujin 28-go (the robot's official designation) from falling into the hands of the bad guys and decide to dedicate him to peace rather than war.
In 21st century Japan, cars with artificial intelligence for increased safety, known as "A.I. cars," have revolutionized the car industry. Special schools teaching children driving A.I. cars have been established. One day, Kakeru Todoroki, a fifth grader of Arcadia Academy, was summoned by the school principal and given an A.I. car "to save the humanity by chosen drivers like you." The car, however, is not just a car but also a transforming robot known as "Gyrozetter."
The hapless crew of the Nadesico is between the powerful Earth Federation forces and the mysterious Jupiterians. They have journeyed out to the planet Jupiter in hopes of rescuing Captain Yurika, but what they don't know is that she may not want to be rescued. How can a lone battleship survive against the amassed power of two planets?