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.
Find all of the hidden costumes.
Take a picture of ALL the creatures.
Collect ALL the Explorer Medallions.
Find ALL the Golden Gears.
Rescue all the baby Pin Birds.
Visit the hidden planet.
Discover ALL the Locations.
Collect all the Explorer Medallions in Crystal Cavern.
Find ALL the Fossils.
Find the legendary treasure.
Meet the requirements to open the Mysterious Gate.
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.
Kick a Bucket Head.
Sometimes, things don't always go as planned.
Discover the mysterious travelling merchant.
Take a picture of the Master Explorer.
Purchase an item from the shop.
Do a triple jump.
Earn your first Explorer Medallion.