Where's cryoling & greenmane

I was on crescent island n a gargoyle summoned one I want to know where or how do I get one.

Possibly one of the Arkadions that are gold egg only. Ive got over 100% of monsters captured, and I’ve never seen them.

greenmane is pvp prize, at 12500 I think. cryoling is a future event monster

Cryoling -> Cryowyrm I believe

Ok thanks