Here is the full list of all 42 Romancing SaGa 2 achievements.
Defeated Dread Queen
Defeated Ruined Memory
Defeated Crushing Memory
Defeated Sinful Memory
Defeated Evil Memory
Acquired Dark Magic
Finished the Game
Defeated Noel
Won Against Victor
Befriended a Diviner
Befriended an Iris
Defeated Subier
Became the Final Emperor
Defeated Rocbouquet
Befriended a Diver
Befriended a Salamander
Coppelia became Emperor
Befriended a Nereid
Befriended a Mole
Befriended Coppelia
Befriended an Imperial Guard
Befriended a Nomad
Defeated Bokhohn
Befriended a Desert Guard
Defeated Wagnas
Befriended a Levante Guard
Befriended a Strategist
Befriended a Ninja
Defeated Dantarg
Befriended a Hunter
Befriended an Amazon
Befriended an Armed Merchant
Befriended a Mage for Hire
Befriended a Saigo Clansman
Befriended a Crusader
Befriended a Vagabond
Befriended a Brawler
Defeated Kzinssie
Gerard became Emperor
Defeated the Watchmen
Nurtured the Avalon Tree to the fullest
Finished Game without Final Emperor