^ Test 0 was in the Japanese version only, according to a site. It was taken out of the US version. It's supposed to be quite tough (has TONS of HP) but if you defeat it, you get 40000 EXP and Gil and 400 (!!) AP.
Here's another odd one that is onviously false, but is quite interesting:
Meteor
Yes, it's the rumored "alternate" final boss. According to the rumor, when you fight Sephiroth as Cloud alone (final), run away from the battle. (This could be the rumor's weak point, as you can't run away from boss battles.) If you succeed, you should suddenly end up outside Midgar. (Dunno how) There will be a long scene and you should enter the battle with Meteor. Meteor is claimed to be a "Sin-like" boss in that if you don't defeat it within one minute, it'll use its Super Attack, "Earth Crush" and you'll get the worst ending in the game. Thing is, since it has 9,999,999,999,999 (!!!!!!!!) HP, it'll be impossible to normally kill it within one minute. In fact, the only way to win is to cast Mini on it 5 times, and then it'll use Earth Crush but it'll only provide as much force as a small rock being thrown on metal. Pathetic I know......I think this is instantly false since Mini shrinks the target to a certain extent if you use it once.
Source:
The Turk Alliance: Over 100 Rumors!