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