List of Mario Tennis Aces online tournaments

This is a list of online tournaments in Mario Tennis Aces. The game holds monthly online tournaments, in which players need to advance through a number of matches (rounds) against other human opponents and beat the finals in order to win a championship. Depending on the degree of participation in these online tournaments, the player can earn various prizes, such as new playable characters and costumes.

The following is a list of all online tournaments hosted from the release of the first demo up until now, along with the participation prizes handed out in each.

Pre-launch demo (May 2018)
Prior to Mario Tennis Aces's release date, a free demo was released on Nintendo eShop, including a limited-time online tournament. Characters could be unlocked for use in this demo by accumulating participation points. The Mario overalls costume could also be unlocked for the full game by completing one online match.

June 2018 - November 2018
In these months, each tournament consisted of three preliminary rounds, followed by semifinals and finals. The player could only choose to play in Standard or Simple modes, both encompassed by the Singles class. The only participation bonus in every tournament (except for the June tournament) was a new playable character, which was unlocked by simply playing at least one round in the tournament.

December 2018
As of December 2018, the tournaments have been reduced to only one preliminary round, followed by semifinals and finals, similarly to the COM tournaments. This tournament also added the Doubles class among the already-existent Standard and Simple classes. Exclusively in this tournament, the player could earn different participation bonuses depending on the class played.

January 2019 - current
The January 2019 tournament introduced Participation Points, which are earned in accordance to the player's performance in a match. By earning enough Participation Points in a tournament, the player unlocks new alternate costumes for certain playable characters. New playable characters are still awarded by simply playing at least one match in a tournament.

Special demo (April 2019 - May 2019)
Another demo was released on Nintendo eShop in April 2019. This demo is similar to the prior demo, although characters are unlocked by playing a set number of matches, rather than by accumulating participation points. With the exception of the Mario overalls costume, these matches can be played either in or out of the limited-time tournament to unlock the rewards. The Mario overalls costume, once unlocked, can be used in both this demo and the full game.