Quote Originally Posted by Lynx
setzer and celes are the only 2 required characters to advance in the game. in WoR you start off with celes and you need setzer to fly inot the last place obviously you need more guys to press all the buttons in kefkas tower but you can decide form there who you want to go and get.
This is inaccurate, actually; in addition to Celes and Setzer, Edgar must be acquired to further the game. Using only these three to finish is often referred to as a CES Challenge.