LogFAQs > #966593593

EchoBaz posted...

So I've seen people fight these bosses from Final Fantasy 6 and other games, and I'm curious what expansion that starts in.

Depends which bosses.

Warring Triad is in HW.
Phantom Train, the painting boss, Guardian, and Kefka are the second tier Omega raid in Stormblood. O8 Savage even goes the extra mile and gives us Kefka's clown god form.
First tier Omega is the bosses from the end of V, with Savage giving us Neo Exdeath, O9 gives us Chaos from I, and the Ivalice 24-man raids is largely FF Tactics with bits of XII sprinkled in for measure.
Endwalker has a ton of IV.

Really, the whole game is sprinkled with bosses from previous games. You just have to be specific with which ones you mean.