As you wouldn't expect from a faction made exclusively of AIs, their line infantry is composed mostly of human soldiers. Specifically, legions upon legions of vat-grown female supersoldiers wearing intrincate, living suits of biomechanical power armor. Despite the extensive modifications to their bodies, both genetic and bionic, and their equipment, the human troopers are very low on the hierarchy of the AI's armies and are usually considered an expendable asset for tasks like probing enemy defenses and dislodging garrison strongpoints.
Whenever inactive, the troopers are tightly stored in stacks onboard spacecraft or garrisons (think the tight human stacking of slave-trading ships) their bodies are electrically stimulated as a form of exercise. They are stored in a state of semi consciousness and undergo mental training, carrying out combat simulations in coordinated collective dreams with the rest of their unit, usually with the ship's brain acting as a server. Simulations vary a lot and are usually based on predictions of the battlefield. When an unit of soldiers gets destroyed, their latest memories usually gets uploaded to the dream network for other soldiers to find their way out of the situation that got them killed. This means the training regime for AI soldiers is as omnipresent as it is ruthless; while other soldiers eat, rest, go on vacations and socialize, AI soldiers are constantly dreaming of upcoming battles while being intravenously fed.
During battle their modifications give them superhuman endurance, resistance to pain and psychological resilience, and are hypnotically briefed before each mission to put the objective above their lives. While they require sleep, they do so like dolphins, with only half of the brain being dormant at any moment. Their combat rations are intravenous, delivered by a mixing system in the suit connected to biometric system that monitor the nutritional requirements of the soldier. They require much less of this proteic sludge than vehicles and can also eat conventionally, though their underdevelopped digestive systems have a hard time coping.
They aren't considered important enough to get fuzzy armor, and instead are protected by layers of ablative-encased superplastic tetragonal zirconia in vital areas, and simple ablative on the limbs. The suit has its own auxiliary power source, but is usually powered by external wireless broadcasts from larger vehicles or ships. Gravitic buffers give them a limited flight ability to counteract the relative bulk of the suits.
Platoons are the standarized unit in which marines are deployed, each one led by a powerful demiorganic soldier significantly more capable than the human troops it commands. These 15-man squads are centered around a soldier equipped with a missile launcher, and through datalink networking can sum the capacities of their individual sensors and achieve the optics and computing performance of larger vehicles.
The service life of the marines is 5 to 10 years after their birth and a two year-long period of adaptation. After they have passed their expiration date, they are euthanized regardless of their actual battle achievements.