https://www.smogon.com/dex/xy/pokemon/xerneas/
Close Combat is in the All-out Attacker section.
Apparently: "Close Combat is a physical Fighting-type move that can break through Blissey, and it can also hit most other Steel-types well. Focus Blast inflicts special damage on Steel-types and doesn't lower Xerneas's defenses, but the cost is reduced accuracy and struggling more against Blissey."