[quote name='GuardianE']Triple Hyper Combo.
It uses up as many Hyper gauges as you have, up to three, one for each character. All three characters will come on screen and perform their respective Hypers based on their assigned assist type. For characters with only one Hyper, that's sort of irrelevant, but for characters like Ken, an Anti Air assist will make him perform his Shinryuken whereas his Projectile assist will make him perform a Shoryureppa. A few characters, Rogue and Spiral, even have special Hypers that can only be activated with a THC.
Otherwise, they're not used all that much except for newbies trying to catch you with three beam supers or something. Hyper Canceling (canceling one hyper into the next character's hyper) is generally a better practice.[/QUOTE]
THC's also come out faster than regular supers by quite a bit. So they're good for catching people if they're down to a last character and you want to chip them or catch them on reaction. Also, some THC's are inescapable, like Sentinel/commando/ x since commands super goes up and then comes down the entire screen straight into sentinels and x's supers if you try to superjump, this is probably the biggest reason anyone uses THC's to chip.