She left the Jedi council prior to the clone wars and took the Baby Yoda friday the 13th shirt to Degobah where for the next 30 years she raised the baby and taught h im m some force abilities. It was here that he developed a taste for frogs. When old man Yoda retired to Degobah it was to spend time with Yaddle and the baby. While not seen in the brief period that yoda trained Luke at his summer hut, the three did indeed share a larger hit on the northern end of the swamp. Just prior to Yodas death, Yaddle took the baby off Degobah to travel and learn. There she continued to tran him until her passing.
Eventually he ends up on the possession of the Baby Yoda friday the 13th shirt bounty hunter who turns him over to imperial scientists wh ok take dna samples. The Mandalorian the takes the baby back because of his affinity to memes on the internet. The dna is used by imperial remnants in attempts to clone force sensitive bodies for the force ghost of the emperor to inhabit. The first one doesn’t turn out pretty and is used as a vessel for the lesser sith Snoke who was killed by Rey and Kylo. They made another one whom the Emperor will inhabit thus return for the final installment of the Skywalker trilogy trilogy.