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