Here is the full list of all 46 Squids Odyssey achievements.
Complete all missions in Pro Mode
Level up all squids from to level 25
Defeat 50 enemies on a Seahorse
Defeat 50 enemies with a jellyfish
Get 3 stars for all bonus missions
Unlock all seahorses
Unlock all helmets in your inventory
Unlock all cursed helmets in your inventory
Level up all squids to level 10
Complete Chapter 8
Get 3 stars for all story missions
Level up a squid to level 25
Recruit Oktoku
Complete Chapter 7
Recruit Magnus
Complete Chapter 6
Hit 6 enemies in one stomp attack
Recruit Cleef
Complete Chapter 5
Complete Chapter 4
Recruit Brad
Recruit Kapono
Defeat 10 enemies in one turn
Complete Chapter 3
Finish "The Spirit of the West" in 1 turn without inventory items
Recruit Ronimo
Defeat 500 enemies
Complete Chapter 2
Recruit Calamary Jane
Use 10 miracle tentacles
Recruit Jammer
Complete Chapter 1
Beat the first Guardian
Each squid should bounce on something at each turn in mission "Holding Ground"
Finish mission "back to the wall" in 2 turns
Level up a squid to level 10
Heal 500 HP with a healer squid
Give a 5 combo melee hit
Do 10 combos in mission "The Iron Throne"
Recruit Venus
Invoke a mighty kraken
Recruit Vesper
Push an enemy in a hole with a shoot attack in mission "Lady in the Water"
Play a mission with the redemption hat
Recruit Sammo
Recruit Clint