First of overdone topic, but that won't stop me repeating successful arguments from other threads (don't remember who initially said this). From gameplay at 255 (max speed with auto haste cloud vs 177 (NOT max) auto haste squall, squall's bar goes up four times faster. I never beefed up zidane but if I remember right he's slightly faster than cloud (maybe a ratio between him and squall of 3:1). Tidus we have no clue of his comparative speed as the systems there don't intermix at all but I will assume a ratio between him and squall of approximately 3:1 (squall's favor) as both he and zidane are speedy characters I'm scoring them equally. All characters start at the beginning of their bar (so it's equal). Lastly I'm assuming all characters are beefed up to the maximum.
The fight:
1.Squall casts aura on himself (at this speed it will last at least 8 turns)
2.Squall heros himself (once again will last a while)
3.Squall renzokuken's Zidane, Zidane auto lifes to 1 HP and his bar starts over
4.Tidus gets a turn, as he cannot attack squall he kills off one of the others, probably zidane to stop him from ever reviving.
5.Let's give this turn to cloud, KoR kills tidus who auto pheonix's and doesn't touch Squall.
5.Squall renzokukens tidus, tidus is out.
6.Squall kills cloud, cloud uses final attack, revive 2.
7.For the next million turns squall's bar fills up faster and he kills cloud everyone of them.
1538205.Cloud's mp runs out, he cannot revive!!!
Clear 1st Squall crushingly wins
2nd Cloud, honorable mention for lasting forever
3rd Tidus
4th Zidane

Or alternatively if people stole hero's from squall...
4.Tidus steals from squall!!! He has about a 1 in 1000 chance of stealing hero but say he gets luck and does... he never gets another turn to use it... so sad=same results as above.

I don't see any problem with the above except arguably tidus' speed being incompatible. Other than that Squall would win a three vs Squall fight. This all based on gameplay.