Is Final Fantasy X the only game in the franchise where you can swap characters in mid-battle?

I'm fairly sure that Final Fantasy X is the first game in the series where you were able to swap characters in and out during a fight, but I'm not certain if it's the only one.

Are there any other games in the series where swapping in "inactive" characters during a battle is possible?

Solution 1:

No, it is not. Final Fantasy XII lets you switch characters in the middle of battle in pretty much the same fashion - to replace fallen allies or just to alter who is taking the brunt of attacks.

I don't know about the ones that come after, but one's enough to say no. ♪

Solution 2:

Final Fantasy X-2 and Final Fantasy XIII both allow characters to freely change roles/jobs/classes/paradigms/whatever mid-fight, but not the characters.

Before the final battle in Final Fantasy VI (FF3 US), you were asked to make a list of all the characters in the game. When you moved from one stage of the fight to the next, any dead characters were swapped out for the next one on your list. This was a one-time thing that only happened for the final battle, though.