One of the new additions to Super Smash Bros. Ultimate is the mechanic of Spirits, which has a utility beyond just being the name of a new mode. You’ll be given a Spirit at the beginning of the game, and you can collect many more throughout, but how exactly do you level up these Spirits to make them stronger?
There’s a couple of ways you can level up your Spirits in Super Smash Bros. Ultimate. The main way is by participating in fights in the game’s single-player adventure mode, World of Light. Spirits of all sorts of characters inhabit the bodies of the game’s fighters, and winning fights against them is probably the most common way of leveling up whichever Spirits you have in your party at the time of the battle. You can also level up your Spirits by feeding them Snacks, which you obtain by winning battles as well. You can feed Snacks to your Spirits by selecting “Level Up” from the “Manage Spirits” menu in the World of Light pause menu or the “Collection” menu in the Spirits mode menu.
Spirits will increase your player characters’ stats, such as Attack power, Defense power, or Grab power, as well as providing some extra abilities, so figure out which Spirits work the best for you and try to level them up as much as you can to create the ultimate fighter.