Eggs in the tomorrow community day

During the event this 2 days specific pokemon will hatch. However, will they hatch in their respective type of eggs or in ANY egg? For example, I think Bagon will be only hatchable in 10 km ones, right?

Correct, and only Bagon and Raltz will hatch from 10km eggs during the event

As I understood it all the CD Pokemon wiil be in eggs (also those from 2018) and they will only be in eggs either the saturday or the sunday

Yes, what I meant to say was only 2 pokemon hatch from 10km eggs obtained during CD each day. So if he wanted Bagon he had a 50% chance of getting it from a 10km egg during Saturday’s CD.