They use 20 or 24 inches and are built for little shredders.
Lil Shredder Prodigy
This brand helps many childrens to shred on bikepark trails.. and most of the time, the daddies follow the rides with a GoPro…
That’s why it is a generator of many buzz on youtube (here is an example: http://www.youtube.com/watch?v=OccGlD2bnnw).
COMMENCAL SUPREME 24
Commencal builds for 2014 a full range of mountain bikes for kids, from 12 inches to 24, hardtail or fully. The Supreme 24 is the “biggest” one and has all the DNA of its brother in 26 inches !
It looks like a old Kona and may be one of the latest ride that use the old DNA of the brand with the big rocker.