Here is the full list of all 13 Zet Zillions achievements.
Get all Trophies
Kill an enemy with a corpse
Kill an enemy with spikes but die in the process
Get more than 30 cards in your deck
Get less than 7 cards in your deck
Win a battle with 7 HP or less
Win a battle without making any fusions
Defeat Thanatos's Left Hand
Defeat Thanatos
Defeat Thanatos with a Voidstone
Defeat Trash Zero
Defeat Archangel
Defeat Thanatos Zero