Just as an explanation for the changes:
"It could use the same abilities as Saïx, but to a lesser extent. Anti-Saïx wields a dark version of the Lunatic, becoming berserk in a means of gaining power. This enemy also has the same amount of health as its Nobody counterpart. Anti-Saïx can only be fought when playing during mission mode."
I simplified this to "It's a dark version of Saix" and "It replaces him in Mission 91", which get the same point across. There could easily be a strategy section, though, that covers this more fully.
"*Anti-Saïx appears in Mission Mode because Saïx is playable. "
This was completely redundant to the lead paragraph.
"*Anti-Saïx doesn't have a voice, as do all other Anti-characters."
This seems to imply that other Anti's have voices, which is untrue - however, none of these guys, or Heartless or Nobodies have voices unless they're human again, so the note is kind of obvious either way.