Despite being a machine under the control of the Black Hole Planet 3 Aliens, Mechagodzilla is semi-autonomous in Godzilla vs. Mechagodzilla, responding to verbal commands from Kuronuma relayed electronically to the Cybanek on its head. In Terror of Mechagodzilla, the rebuilt Mechagodzilla 2 is linked to the cyborg Katsura Mafune, and is controlled through her organic brain tissue. However, Mechagodzilla seems to retain some autonomy, as it continues fighting Godzilla even after Katsura breaks free of the Black Hole Planet 3 Aliens' influence and regains complete control over her mind.
Mechagodzilla is an extremely brutal hand-to-hand combatant, shown when it breaks Anguirus' jaw and repeatedly pummels King Caesar and shoves its hand down the monster's throat during their battle. However, Mechagodzilla primarily relies on its vast array of weaponry and prefers to attack its opponents from a distance using its various missiles and lasers. The 1992 book Special Graphix Godzilla vs. Mothra compares Mechagodzilla's personality with that of King Ghidorah and Gigan, two other recurring villains in the Showa series.