I have half a billion Kogo parts to I can help with this pagehttp://soliaonline.wikidot.com/kogo:available
Kogo Drops have a pattern:
Whatever the baby drops, the adult will drop too with minor edits. In cases like Alrune, the middle evolution seems to match the baby.
-Each Kogo has an item specific to its species that only the baby will drop, or only the adult will drop here's the list.
Aky Baby: Fangs
Aky Adult: Claw
Constella Baby: Stars
Constella Adult: Star Board
Alrune Baby/Juvi: Tail Flower
Alrune Adult: Ear Fluff
Byakko Baby: Tail Shards
Byakko Adult: Whiskers
Kibbit Baby: Vine
Kibbit Adult: Leaf
Owprin Baby: Down Feather
Owprin Adult: Leaves
Kitorn Baby/Juvi: Ear - Judging by low drop rate, I haven't turned in adults to officially compare.
Name Unknown, seen in announcement. Judging it to be the adult item because its a part of the mask only the adult wears.
I don't know Axi, I haven't started to turn any in yet. Wanted to try to breed them first to get more.
-The item that is unique seems to be rarer then the other drops, Essence seem to be most common - every Kogo has an essence.
-They have an item based on Element, babies drop sparkles, adults drop gems. All Sparkles and Gems are the same just different colors.
-They have an item based on their Type and stage as follows:
Baby Items: Beast Fur, Bird Feather, Plant Rood, Dragon Fang
Adult Items: Beast Fang, Bird Talon, Plant Pollen, Dragon Scale
From event's but unsure which drops: Fish Scale, Bug Stinger
I'd edit it myself but I'm honestly afraid of mucking up these pages. I wish it was on Wikia, it was soo much easier to edit.