Here is the full list of all 19 Finding Teddy achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
You unlocked all artworks.
Tarant showed you his Nyan Cat talent.
You beat the game and unlocked all the content.
You found all fireflies.
You helped the Spider Mother to get back it's lost baby.
You helped the ghost to transmit a message.
You unlocked all the Musicom.
You beat the game and saved Teddy.
You died against Tarant.
You died against the second Spider.
You found a firefly. Find them all !
Mr Cat joined you.
You died against the Snake.
You died against the Crocodile.
You died against the Spider.
Mr Bug joined you.
You died against the Blob.
You died against the Monster.
You died against the Wasp.