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.
Collect ALL the Explorer Medallions.
Find the legendary treasure.
Take a picture of ALL the creatures.
Find ALL the Golden Gears.
Meet the requirements to open the Mysterious Gate.
Discover ALL the Locations.
Find ALL the Fossils.
Collect all the Explorer Medallions in Crystal Cavern.
Collect all the Explorer Medallions in Sinking Sands.
Visit the hidden planet.
Collect all the Explorer Medallions in Mount Magma.
Rescue all the baby Pin Birds.
Take a picture of the Master Explorer.
Find a hidden hat.
Collect all the Explorer Medallions in Cozy Canyon.
Collect 10 Explorer Medallions.
Hey, watch where you're rolling!
Kick a Bucket Head.
Sometimes, things don't always go as planned.
Discover the mysterious travelling merchant.
Purchase an item from the shop.
Earn your first Explorer Medallion.
Do a triple jump.