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