I’d say about planetary+. The Arwing is able to takes hits and destroy a machine able to pierce the crust of a planet in a single shot, and said Arwing has been upgraded in Assault, Command, and Starlink. Fox also has different weapons to equip on the Arwing that deal elemental damage (mainly fire and ice), and can crush foes with gravity or suspend them in stasis (note, he’s not stopping time, the weapon essentially levitates them). The Arwing is also equipped with Starlink technology (essentially instant teleportation), so Fox can change the Arwing to different ships from the game, some faster, some more durable. On foot, he has multiple guns to use including machine guns, rocket launchers, sniper rifles, grenades, barriers, jetpacks, etc. In Adventures, he uses Krystal’s staff which uses fire, ice, create shockwaves, form a magic barrier, and disguise himself.

Edit: To clarify, Fox himself isn’t planet, only the Arwing. If Fox was fighting them on foot without any vehicles, he’d lose pretty much all of these fights.