As your party gains experience, they develop newer and more powerful combos. To use these combos though, the player must input the proper sequence of buttons. A simple combo may be triggered by pushing two buttons in sequence while more complex and powerful combos require anywhere from four to five button sequences. There is even an option to save combos and then unleashing them in one massive attack on a powerful foe. The system is based on AP or attack points. A normal attack in Xenogears has three options depending upon the number of AP you want to expend. Each option is represented by a button on the controller, and depending on the number of AP available to you, you choose the attack you want to execute, or if they are available, the combo you want to use. A combo is nothing more than a combination of the three option attacks in a certain sequence.

On the Xenogears battlefield, even powerful fighters must bow to the power of the giant robots, technological wonders from centuries ago. These giant armored robots are also capable of combo attacks, though to be truly effective, they must first power up through the execution of normal attacks. Each attack attempt charges up one attack level. The higher the level of the pilot, the higher the level a robot can charge to. The only draw back to the robot is that unlike people, they do not level up; they must be upgraded by buying new parts and equipping better items. Still, even the weakest robot is more than a match for an army of men.

Of course, you are not limited to only physical fighting; Xenogears characters also develop "Ether/Chi" or magical attacks which serve a variety of functions from healing and warding to mighty offensive attacks. Some may wonder why a fighter as gifted as Fei would ever need to deviate from physical attacks. The answer is simple; in a world as large as Xenogears, brute force is not enough; there do exist enemies which are in fact immune to martial arts. Ether attacks may be the only way to overcome some of these adversaries.

Ether attacks are also an integral part of robot combat. A mystical connection between the robot and its pilot allows the pilot to channel, and in some cases, amplify the Ether/Chi abilities he or she possess through the robot itself.