The younger forms of the ultra beasts has appeared across the hazama region as the ultra beasts started to freely live in there. Younger form has the same attacks, but its stats are lowered. With training and gaining a certain level the ultra beasts will grow into their adult form!
Also little explanation:
Nihilego's baby form consists of 3 organisms that attached to each other from the birth and the last one in the chain has to deal with getting food, while other two are sucking nutrients out of it untill they grow up.
In teenage form the first nihilego in the chain is laboring its brother/sister to get food, while it itself just sucks on nutrients of the last nihilego in the chain. An interesting concept of a parasitic relationship between relatives, isnt it? Also reversing the formula of some pokemon evolutions: it becames more of them after evolution.
Kartana's child form is a noodle box and also a flower. The parent kartana will bring food to its child and place it in its box shaped body, where the little one will consume it and discard the remainings by flipping over.
Buzzwole's child form is a mosquito larva that will move in the water by flexing its arm tail limb.
by James_the_nickit