You can. From the main menu, go to Friends/1P > Create Lobby
From here, you’ll have two types of lobbies to choose from:
Party: Fight in a variety of stages and modes using customizable rules. Maximum of 10 consoles per lobby.
Arena: Take turns fighting in one-on-one matches while everyone else spectates. Maximum of 4 playersw per lobby.
Choose the lobby you want to create.
Then, get your friends to go to Friends/1P on their own consoles and select your name from the menu.
As the host, you can set the rules for the lobby. These options include:
Party: You can choose from a selection of presets or make a custom ruleset of your own. You can change:
The number of ₳ needed to win
Which game modes can appear
The number of players allowed in each game mode
Whether or not items can appear
Whether or not streak bonuses (Lucky Break/Win Streak Challenge) can occur
Which stages can appear
Arena: There are no presets for Arena lobbies. You can change: