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