Royal Companions are front runners among all troops, with a great deal of hitpoints, they can endure more than any other troop. For their strength in taking damage, they do sheer damage themselves and cannot win battles unless they are supported by stronger troops.
As a Greek unique unit, the Royal Companion has more 10% more health than standard heavy cavalry and 25% more damage.
The Royal Companion is one of the strongest units in the game; as well as the strongest heavy cavalry.
The Royal Companions were the premier Macedonian cavalry unit. Commanded by Alexander himself and composed of Alexander's most trusted friends and soldiers, this was perhaps the deadliest single cavalry unit in the ancient world. In battle Alexander led this unit in a wedge formation with himself at the pointy end and thus the first to smash into the enemy.
Royal Companions have a lot of health but are slow and have low attack power, so use them in groups.
Royal companions are weak against many defenses grouped together.
Due to their high health, royal companions can be use as meat shields to protect infantry from the defenses.
Ballista Towers can destroy royal companions easily like all heavy cavalry. If you can, try swarming it with heavy infantry or ranged infantry to destroy it quick enough since the ballista tower is slow.
When pushing for trophies, you would need to destroy the Town Center. In many bases, the town center would be in the center of the base. First, train up an army of royal companions and a wall miner. When attacking, deploy a wall miner and wait until it destroys the necessary walls, then deploy all your royal companions in the areas which the Town Center is more close to. If there are a few defenses blocking the way, destroy them. Then rally your royal companions to destroy the Town Center.
Royal Companions would ignore defensive troops and would pursue their targets which are defensive buildings. However, if a defensive troop attacks the royal companion, the royal companion will attack back until the defensive troop is killed; thus making the royal companion distracted. Try to use and deploy ranged infantry such as archers or heavy infantry such as phalanxes after deploying the royal companions to eliminate the defensive troops.
Royal Companions are a good alliance troop due to its high health; making it longer to kill them. However, they take up 6 space in the alliance gate so it cannot be used in a level 1 Alliance Gate in the Iron Age (which can only hold 3 spaces) until it is upgraded to level 2 which is available in the Classical Age.
A misconception in the photo above is that the companion seems to be wearing a Galea helmet (a Roman helmet). Royal Companions would wear Boeotian helmets instead since it allowed good peripheral vision and unimpaired hearing. Royal Companions would also wear a bronze muscle cuirass, linothorax (linen upper body armor), and shoulder guards. Another misconception is that companions don't use shields. The shield also has the lambda sign on it which represents Sparta. Sparta would never used cavalry such as companions and would rely on infantry such as hoplites and phalanxes.
Companions uses 2 weapons; the xyston (a spear, the main weapon of the companion) and a kopis (curved slashing sword) or xiphos (cut and thrust sword) which is used for close combat and a replacement if the xyston breaks. The image shows the companion holding a xiphos.