Uber Rare Cats (Japanese: 超激レア) are a part of Cat Units and can be unlocked by playing the Rare Cat Capsule. When rolling a Rare Cat Capsule, the player has a very small chance (~3%-5%) to get an Uber Rare Cat from the current set (pool). Usually, the pools change each 4 days without following any regular schedule.
Sometimes, there are special offers: Triple chance slightly increases the chance to get an Uber Rare Cat, while 100 % Uber Super Rare (also known as "Guaranteed Gacha") allows the user to have an Uber Rare Cat for sure, if and only if they exchange Cat Food with an 11-times draw. The Step-Up blitz process guarantees the player an Uber Rare Cat if the 11-times draw is taken 3 times successively, within the event frame (2 million XP are also offered).
For the full article, see here.
The following events simply contain combinations of Uber Rare Cats from multiple other gacha sets. Red Busters and Uberfest are in regular rotation, whilst the others were part of seasonal events. Note that Uberfest greatly increases the chance to get an Uber to ~9%.