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