After several years of running tournaments offline, Super Smash Bros. Ultimate is finally being updated with online amiibo support with version 3.1.0 of the game, which is releasing very soon.
Now you can send your amiibo off on journeys to train via the Games & More > amiibo menu! Send your battle-hardened FPs out into the wide world to spar with other FPs! amiibo you’ve sent on a journey will relentlessly pursue their training until they come home! FPs can now join Battle Arenas. Show everyone the power of a trained amiibo!
According to this message uploaded to the Super Smash Bros. servers (which has not gone live yet), amiibo will be able to join Battle Arenas and a new online mode. The amiibo metagame is about to grow even more. We’re working hard behind the scenes with new guides and posts, so stay tuned!