Here is the full list of all 25 Poi achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
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.
Find a hidden hat.
Kick a Bucket Head.
Visit the hidden planet.
Take a picture of the Master Explorer.
Rescue all the baby Pin Birds.
Discover ALL the Locations.
Collect all the Explorer Medallions in Mount Magma.
Collect all the Explorer Medallions in Crystal Cavern.
Collect all the Explorer Medallions in Sinking Sands.
Do a triple jump.
Collect 10 Explorer Medallions.
Collect all the Explorer Medallions in Cozy Canyon.
Sometimes, things don't always go as planned.
Hey, watch where you're rolling!
Find ALL the Fossils.
Discover the mysterious travelling merchant.
Purchase an item from the shop.
Earn your first Explorer Medallion.
Beat the game in New Game+ mode.