How?
Through this guy, the leader of the Timber Owls.
Despite being the group’s leader, Zone often lets Rinoa do the talking and take responsibility for the tougher tasks. He gets coincidental “stomach pains” whenever much pressure is laid upon him or he is asked to participate in the more dangerous missions. One notable example is when he decides to let Quistis have his train ticket to escape Timber, but when she tries to thank him he doubles over in pain and runs away.
To where does he run away? The bathroom. But what implications does this have on Final Fantasy VI? The entire world of Final Fantasy VI resides within Zone’s stomach.

The World of Balance is Zone’s stomach in harmony. He’s eating good, feeling great, and has no relatively stress. His diet consists of rabbits and crows.

The World of Ruin is Zone at his most frustrated. His upset stomach causes a shift in his intestines. Somehow, Kefka “upset” Zone’s balance, and now his insides, and the rest of the world suffers. Kefka is truly an evil agitator.
So when people are falling from platforms in the World of Ruins, they’re probably drowning in the toilet. If we could hear his stomach from the inside, it would probably sound like this.
Of course, this is no ordinary stomach pain. Zone has unwittingly eaten a tapeworm, our characters know as the Zone Eater.
The Zone Eater is an enemy in Final Fantasy VI that only appears on Triangle Island in the World of Ruin. Its only attacks are Gravity, Inhale, and Freezing Dust, thus, it is incapable of killing the party members. The true purpose of the Zone Eater is to recruit the optional character Gogo from inside the monster’s stomach. To do this, the player must wait for the Zone Eater to inhale their party members ending the battle when the entire party is eaten and spawning them in the Zone Eater’s belly.
The Zone Eater eats our characters. In a sense, the Zone Eater’s real name is “Zone’s Eater” – as in Zone’s tapeworm, who eats the characters. Eh? EHHHH!?
Zone’s Eater coincidentally surfaces right in the World of Zone’s Ruined Stomach and contains Gogo.
This would also mean the Interdimensional Rift Gogo travels from Final Fantasy V to Final Fantasy VI exists within Zone’s tapeworm since s/he resides in the stomach of the Zone Eater’s…the X-Zone.
So tHeN BaRtZ, lEnNa, FaRiS, kRiLe, GaLuF, gIlGaMeSh aNd eVeN Ex-dEaTh aRe, In pArT, iN A PaRt oF ThE InTeR-DiMeNsIoNaL TaPeWoRm iNsIdE Of a nOn-pLaYaBlE FiNaL FaNtAsY ViIi cHaRaCtEr’s sToMaCh tHrOuGh tHe pRoPrIeTy oF SpAcEtImE AnD QuAnTuM MeChAnIcS, wHeReAs iN ThE PrOpEnSiTy oF HiS NaTuRe eX-DeAtH SuMmOnS ThE VoId iN WhIcH –
Gary, what you’ve just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone is now dumber for having read to it. I award you no karma points, and may God have mercy on your soul.
Sorry guys, this theory is literally shiitake.