This page explains how to obtain Ending 4: “The Shop Staff and the Three Unlikely Heroes” in Chrono Cross: The Radical Dreamers Edition.
How to Obtain Ending 4
You can achieve this in a New Game Plus by speeding through the beginning of the game, up to Viper Manor where Kid gets poisoned. To keep things varied, we suggest not saving Kid (since you’ll need to save her for Ending 3).
Or if you kept a save file before completing Fort Dragonia, you can Continue Plus to that–and it should work. Provided Nikki and Razzly aren’t both present.
Anyway, during this window of time, return to Opassa Beach (any world) and use the Time Egg to fight the Time Devourer. Refer to the method that doesn’t use the Chrono Cross since, well, you don’t have the Chrono Cross.
Since you’re relatively far into the game, it shouldn’t be too hard to form a decent team. If you didn’t save Kid, you’ve got Glenn who’s a powerhouse.
Bust up the Time Devourer and you’ll earn this ending. It’ll begin with Lisa, the Element Shop girl, who’s gained a shocking employee. Afterwards, it’ll cut to Fort Dragonia where an unlikely trio make their way to the apex. This is probably one of the funnier endings, although the very last bit is somewhat disturbing…
See Ending 4: The Shop Staff and the Three Unlikely Heroes.