Type-3 Kiryu, otherwise known as the Millennium Mechagodzilla, is bio-robot constructed by the Anti-Megalosaurus Force to combat Godzilla after his return in 1999. Kiryu is constructed around the skeleton of the Godzilla who originally attacked Tokyo back in 1954. Kiryu was programmed with special "DNA computers" designed to make it operate like an organic creature, although the DNA sequence used in these computers had the unintended effect of leaving Kiryu susceptible to Godzilla's roar, which reawakened the original Godzilla's spirit and caused Kiryu to go berserk. This was proven in their first encounter after Godzilla had roared prior to retreating back into the ocean, Kiryu began to attack the city of Hakkeijima until the AMF had to force their machine to exhaust his power supply of 2 hours. Kiryu was recalled and his programming altered so this incident could never occur again, then was sent out against Godzilla a second time when he landed at Tokyo. Kiryu fought Godzilla to a draw, leaving the latter with a gruesome chest wound and the former losing an arm and ruining the Absolute Zero Cannon.
Kiryu was rebuilt over the course of a year with new upgrades as “Modified Type-3 Kiryu”, and was sent into combat with Godzilla again when he returned to Tokyo. Kiryu wasn’t alone, however, and had Mothra and her twin larvae join the battle. Kiryu triumphed against his organic counterpart by reopening the wound on Godzilla's chest. But rather than kill him, Kiryu (while possessed by the original Godzilla) took the incapacitated Godzilla and the two sunk into the Japan Trench.
Credit to the listed feats goes to this respect thread on Reddit.