As the Legendary Spear Hero, it should go without saying that Motoyasu is pretty advanced with spears in general. He has to be, as his Legendary Weapon prevents him from wielding anything but spears. However, it takes more than being a talented spearman to be as deadly as Motoyasu is. Granted, much of his power is due to the Legendary Spear itself, which, like all Legendary Weapons, can copy the abilities of other weapons and materials. As such, Motoyasu has a veritable Swiss Army knife of different spear abilities to pick from.
Two of the most common spear abilities you see from the hotheaded Motoyasu are Chaos Spear and Air Strike Javelin (via Shield Hero Wiki). The former of these splits the end of Motoyasu's spear into multiple different points, all of which attack a target at once. Meanwhile, Air Strike Javelin allows Motoyasu to summon a throwing spear for long-ranged combat. Motoyasu also has many other abilities, but some of the more unique ones include Windmill, a defensive technique that can create tornadoes, and Portal Spear, which allows Motoyasu to teleport himself and others to a certain location.