Jelly Sets are a mechanic introduced on September 28th, 2018 in The Legend of the Millennial Tree update, with the release of Pomegranate Cookie. Jelly Sets are sets of alternately designed Jellies that replace the default designs during gameplay, viewable in their own tab in the Jelly Atlas.
The Jellies in a set are collected separately, but typically from the same source. Jellies from different sets can be used freely, even when the full set isn't owned. Jelly shapes are completely cosmetic, but collecting every Jelly shape in a set gives 200 Crystals as a reward.
The initial release of Jelly Sets in 2018 allowed the player to alter the designs of Basic Jellies, Yellow Bear Jellies, Pink Bear Jellies, and Giant Bear Jellies. An update on June 29th, 2020 also added the option to change the designs of Frozen Bear Jellies and Rainbow Bear Jellies.
Obtaining Jelly Sets[]
The Jelly Shape Gacha can be used to obtain individual Jelly Shapes using Rainbow Cubes or Rainbow Beans. Not all Jelly Shapes appear in this Gacha. Special Jelly Shape Gachas give a higher chance to receive a certain set's Jelly Shapes within a limited timeframe.
Jelly Sets are primarily distributed in microtransaction packages, referred to as "New Update Packages" in the Jelly Atlas. The Basic Jellies in New Update Packages are often given for free, with a popup allowing players to exchange 
2 for the Basic Jelly shape and 200, for the Jelly and a Crystal profit. This encourages them to buy the other Jellies to complete the set.
Each season of Champions League and Guild Run have associated Jelly Sets available in the Medal Exchange Center and Guild Shop, respectively. Cookie Affection Jellies are included as the Basic Jellies in Champions League sets and a few other sets, so they are not bought with Champions Medals.
Occasionally, an Event will reward a Jelly Set, and some sets have more unusual unlock conditions. The Pumpkin Party set is rewarded for owning a certain amount of Costumes, the Millennial Tree set is bought at the Breakout Shop, the Tastiest Music Set is redeemed using a coupon included in the CookieRun: Ovenbreak Original Soundtrack, and the Nice to Meet You! set is a very limited set received from going to fan meet-ups or winning giveaways.
Most Jelly Sets are limited, and once the associated update or season ends, they become unavailable. Later Events can rarely bring back old Jelly Sets, such as the Moonlight of Dreams set releasing in the first The City of Wizards (event) and returning for purchase during The City of Wizards: The Wizard Archives, or the Baisc 401 Set being an event reward from both GingerBrave's Trial on April Fools 2019 and GingerBright's Trial on April Fools 2020.
