Here is the full list of all 25 Poi achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Beat the game in New Game+ mode.
Collect ALL the Explorer Medallions.
Take a picture of ALL the creatures.
Find all of the hidden costumes.
Find the legendary treasure.
Find ALL the Golden Gears.
Discover ALL the Locations.
Rescue all the baby Pin Birds.
Visit the hidden planet.
Meet the requirements to open the Mysterious Gate.
Find ALL the Fossils.
Collect all the Explorer Medallions in Crystal Cavern.
Take a picture of the Master Explorer.
Collect all the Explorer Medallions in Sinking Sands.
Collect all the Explorer Medallions in Mount Magma.
Hey, watch where you're rolling!
Find a hidden hat.
Collect all the Explorer Medallions in Cozy Canyon.
Collect 10 Explorer Medallions.
Discover the mysterious travelling merchant.
Purchase an item from the shop.
Kick a Bucket Head.
Sometimes, things don't always go as planned.
Do a triple jump.
Earn your first Explorer Medallion.