Beat the game after beating Dalton, and recovering the Epoch, but before resurrecting Crono.
The Dream Project
There are two ways to receive this ending, on New Game +, at the millennial
fair, go through the right part of the Telepod and then beat the game (you will
be taken to the final boss battle), or defeat Lavos at the ocean palace.
The Successor of Guardia
Defeat Lavos and beat the game after returning from 600 AD for the first time
(use the right side of the Telepod).
Good Night
Use the bucket at the end of time when you first arrive there, i.e. just after you leave 2300 AD for the first time.
Legendary Hero
Fight Lavos after defeating Zombor on the Zenan bridge but before receiving the
Hero Medal.
The Unknown Past
Beat the game after getting the Hero Medal but before going to 65,000,000 BC.
People Of The Times
Defeat Lavos after receiving the Dreamstone but before talking to Frog when you
have the repaired Masamune.
The Oath
Complete the game after giving the completed Masamune to Frog but before going
to confront Magus.
Dino Age
Crush Lavos after defeating Magus but before defeating Azala and the Black
Tyrano in 65,000,000 BC.
What the Prophet Seeks…
Defeat the game after Azala's demise but before battling Lavos in the ocean
palace.
The Oath
Complete the game after giving the completed Masamune to Frog but before going
to confront Magus.
A Slideshow?
Beat the game after seeing Schala use her pendant to open the door to the
throne room/Ocean Palace but BEFORE charging up Marle's pendant at the Mammon
Machine.