Both Roselia and her shiny variant have already been available to trainers in Pokemon Go because she belongs to an earlier Generation, but her baby form, Budew, is only just now being released to trainers as one of the first Sinnoh Pokemon to join the festivities.
Trainers are able to hatch both regular and shiny versions of Budew, the first baby from Generation IV to be released in Pokemon Go. Babies are only available to be obtained by hatching. In addition to Budew, Generation IV will also bring other babies such as Mime Jr., Mantyke, Munchlax, and Bosly.
Niantic also has released Buizel and Floatzel, though it is only confirmed that Buizel is obtainable by raids for now. Some players reported seeing some in the wild, but they were quickly removed from the game showing it to be a mistake. Still, they were on the list that was rumored to be included in the next wave of Generation IV releases of creatures originally introduced in Pokemon: Diamond and Pearl, so maybe there is something more to be seen there.
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