Super Mushroom vs. Super Star

Super Mushroom (Super size) vs. Super Star (Invincibility) is an upcoming Splatfest event in Splatoon 2 that will celebrate the 35th anniversary of the Super Mario Bros. series. It was announced during the Super Mario Bros. 35th Anniversary Direct on 2020-09-03.

Details
The Splatfest theme is about two power-ups from the Super Mario Bros. series: the Super Mushroom, which grants super size, and the Super Star, which grants invincibility.

Merchandise
Splatfest T-shirts based on the artwork for the event were made available to purchase at the My Nintendo Store soon after the announcement. They are also available on Nintendo's online stores for South Korea and Hong Kong. Additionally, Splatfest keychains can be bought for 100 Platinum Points in North America, Europe, and Japan.

Collectible medals
To celebrate the Super Mario Bros. 35th Anniversary, special medals are available for participants in Japan and Europe. Medals will be awarded to the top 100 players of each team and, in Japan only, 100 random others will receive the medals as well. On 2020-12-09, Nintendo revealed further information about the collectible medals within Japan, of which some translated details are listed below.

Further lottery for 100 people:


 * Double chance of winning a medal for those who participated in the event even if they did not rank high! The same premium medal will be presented to 100 of all participants by lottery.
 * Players must have participated in at least one Splatfest battle.
 * Both Normal and Pro mode battles are eligible for the lottery.

Precautions for participation:


 * If the player changes the country or region registered in their Nintendo Account after the event, they may not be eligible to receive a medal.
 * Those who perform actions that Nintendo deems inappropriate, such as fraudulent results or intentional disconnection of communications, may not be eligible for the gift.
 * If there are multiple players with the same Splatfest Power, the player who reaches the level first will be ranked higher.
 * A maximum of one prize can be presented for each Nintendo Switch. If multiple Nintendo Accounts from the same system win, the account with the highest Splatfest Power will be eligible for the medal.
 * The result of the event will be notified by e-mail only to those who are eligible for the gift. Please note that individual inquiries or the ranking of individuals cannot be answered.
 * Nintendo will contact the recipients of the gift to the email address registered in their Nintendo Account by 2021-02-28. If the email cannot be sent, the reward will be invalid.
 * If a player using a child account is eligible for the gift, an email will be sent to the registered email address of the family administrator of that account.
 * Those who are eligible for the gift will be required to complete the free shipping procedure for this prize at the My Nintendo Store.
 * Prizes can only be shipped within Japan.

Trivia

 * This is the first Splatfest with an original theme since Chaos vs. Order - the event that was officially dubbed as the final one.