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