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