Here is the full list of all 21 Super Hydorah achievements.
Destroy Hydorah and all his seeds using no continues.
Unlock all achievements!
Find all hidden secrets in the game.
Score 500000 points or more.
Find the chest of Grialia.
Score 450000 points or more.
Score 400000 points or more.
Destroy Hydorah.
Find a floating blue stone.
Find a giant green egg.
Destroy Hydorah and all his seeds.
Find a jumping flower.
Score 300000 points or more.
Score 350000 points or more.
Find a pink elephant.
Score 250000 points or more.
Score 200000 points or more.
Score 150000 points or more.
Score 100000 points or more.
Score 50000 points or more.
Find an escaping astronaut.