G-Type is composed of living solar plasma, plasma heated by nuclear fusion. His "skin" burns at the temperature of 6000 degrees Kelvin, the approximate temperature of the Sun. This is roughly equivalent to 10,000 degrees Fahrenheit or 5,730 degrees Celsius. He can fire heat blasts from a gem placed on his forehead. He could also project hot plasma from his hands and nozzles mounted on his wrists. He is wearing an armor which prevents his powers going overboard and incinerating people in his proximity.
G-Type was engineered in the "stellar nurseries of Hodinn" in order to serve the Shi'ar Empire. He has mentioned knowing Araki since infancy. In "New X-Men" vol. 1 #124 (May, 2002), G-Type was assigned to execute Cyclops and Xorn. However Xorn used the star in his brain to cause a reactor failure in G-Types plasma core, temporarily incapacitating him. In #125 (June, 2002), G-Type had recovered already and informed Lilandra of the prisoners' escape. Cassandra Nova had Lilandra order him to execute Araki. He regretted the order and begun to do so when ambushed by Xorn. Xorn dissipated G-Type's energy, effectively killing him.
A new G-Type later apparently took his place.