This is a summary of the previous parts of the storyline, which have vanished.
Prologue
It all started when a Lugia went out for a swim in the ocean. All of a sudden, he got trapped within a whirlpool that appeared out of nowhere, and the ocean's water got funneled into him, swelling him out like a balloon.
But to his surprise, the whirlpool did not cause him to burst, but rather, caused him to drink up the entire ocean dry without much harm whatsoever. The ocean's Pokemon soon beckoned out to him for their loss of habitat. The crafty, ocean-sized Lugia suggested they all take up residence in his stomach where the ocean once was, and swallowed them with glee.
Whether it was intent or by accident, Lugia's stomach began to digest the entire ocean, and soon the ocean was no more but blubber padded on his once insignifcant body. The legendary Pokemon of each continent soon went after him with the intention of revenge for his crime, but his psychic powers proved too much for them, and they were all defeated - Groudon, in particular, got to enjoy eating cities for a while before being devoured by Lugia, and Rayquaza fired an ill-placed Hyperbeam when he was being swallowed by Lugia, blimping him up to cover the entire surface of the planet, as well as considerably augmenting his powers.
Brief Respite
When the rest of the legendaries came to, they were being imprisoned by Lugia on top of his chins. Only Ho-Oh, Entei, Raikou, Suicune, Moltres, Zapdos and Articuno were left as the others were seemingly eaten by Lugia as snacks. Lugia forced Ho-Oh to swallow Articuno, but the show was interrupted by Victini who happened to pass by to settle the score, challenging him to eat the world - then see who would come out on top.
Despite the size difference between them, Victini felt himself still up to the challenge and attempted to make his way down to the covered world below, but got stuck in between Lugia's butt fat. Lugia dispatched Ho-Oh to seek him out and bring him back to him, which she did, but as Lugia fell asleep, she swallowed Victini herself in a gamble, which worked. Victini performed a V-Generate within her stomach, and the immense amount of energy absorbed by her stomach caused Ho-Oh to put on a massive amount of weight, allowing her to rival Lugia (as well as sending the rest of them flying off in all directions.)
Soon Victini realised that his escape move had backfired, he made his escape by cutting a hole in her stomach and swimming through her newly formed fat. Lugia began to sleep talk in his dream, and Ho-Oh played along, almost scoring him in her stomach without a struggle, but he woke up halfway.
The awakened Lugia realised that she was immobile and therefore no threat, and began to eat the world himself. Ho-Oh, powerless to stop him, got the rest of the legendaries to ally with her to distract Lugia, while she attempted to swallow him by the tail.
Victini makes allies
Victini soon made his way to the surface, and there he met Celebi and a pair of surviving trainers, June and Purple. After unsuccessfully convincing Celebi that he was not out to eat the world himself, Purple captured Celebi himself with the notion that she was a legendary Pokemon - soon realising he had ran out of Pokeballs to catch Victini himself. With Celebi gone, Victini convinced the trainers instead, and managed to get on June's good side, allowing him access to her Miltank.
Victini used the same technique earlier in Ho-Oh to fatten up the Miltank massively, boosting them upwards to the surface and interrupting Lugia and Ho-Oh. Once there he took the Pokeball containing Celebi, and ate the Pokeball. Tricking the scared Celebi into using her powers to escape he managed to gain some considerable weight himself.
The legendaries with Ho-Oh did not give up. They attacked the two trainers on Miltank, and recalled Miltank back into her Pokeball, leaving a great big void below them, with the legendary birds bringing them and the trainers to safety. Lugia and Victini began to continue the feast of the world, but were forced to stop by Ho-Oh's gut expanding to fit the swallowed Pokeball with the Miltank, covering the world and ousting them upwards. Lugia rolled down like a massive boulder, and in the momentum he was swallowed whole by Ho-Oh, giving her two gut-popping continental meals in less than a few minutes. Victini however just managed to hold on, with Ho-Oh herself taunting him.
June sought retribution for her lost Miltank, and tinkered a device that could fire a beam to fatten Pokemon near instantly. Purple then set out his Pokemon to trick Ho-Oh's company into coming to their location, in which June ordered her Clefable to sing, putting them to sleep, then bloating them to immobility with the beam.
Lugia avoided being digested by Ho-Oh with his psychic powers, and tricked her into eating the remains of the planet, inciting the wrath of Unova's legendaries, Reshiram and Zekrom. Zekrom broke Ho-Oh's trance with a lightning bolt, then they set out to find June.
An old friend!
After Ho-Oh was overturned by Lugia upon failure of his plan, Victini landed onto Unova, and was about to get ready for his next meal - until he saw a pair of massive tails coming out from a building in the distance. Victini soon found out that it was his Floatzel friend, Floaty inside, who had taken up residence inside the abandoned shopping complex, and ate his way to bigness, getting himself stuck in the building. After exchanging some friendly banter Victini pulled him out from the building, and has the building for a meal himself much to Floaty's shock.
Floaty soon got over it though, and was beginning to eat supposedly inedible objects with no problems just like his friend. With the aid of Victini he snacked on the ruined Tubeline Bridge, but their reunion was cut short by Lugia, who shifted his weight around and destabilising the region they were on. Floaty and Victini were then seperated.
Floaty himself ended up in a massive cave network, where he got stuck in the entrance. Meeting a lone Drilbur who was tunnelling through, he convinced the mole Pokemon to free him in exchange for some food caught in his chin folds. Once free the Drilbur accompanied the Floatzel, eating ice cream while the river otter chomped away hungrily at the cave rock.
Strange Discovery
As Floaty ate the cave he stumbled upon an underground city. It was ancient in appearance, but massive. Mountains upon mountains of food were piled up there for some strange reason, giving him reason to feast further, but a similarly fat Luxray was already there before him, challenging him to an eating competition.
Floaty himself lost the competition, being devoured by Luxray. However as he went inside, a statue that was trapped in his fat came to life in the damp environment, revealing itself to be a normal-sized Vaporeon. While she was initially scared by the Floatzel's appearance at first, she introduced herself to be Valerie, the greatest Vaporeon who landed the entire world in her belly two centuries ago. She soon convinced Floaty to get her up to speed with regaining her size, and they soon warmed up to each other, becoming (quite massive) lovers.
Using Valerie's abilities they escaped Luxray in a mist, but they ended up conjoined in the same body as they reformed! It was not a setback at all however, as they could easily take turns eating and resting. The shrunked Luxray soon pleaded for his life, but Floaty swallowed him in lieu of his hostility earlier in the city.
The contest continues
Floaty soon came belly to belly with his friend Victini as the Luxray's energy caused his weight to instantly multiply. Valerie overheard their conversation, and it turned out that they were mortal enemies in a previous life as Victini betrayed her, eating her offspring. She took control and confronted Victini, and as he charged a V-Generate and attempted to annihilate the both of them, Luxray intervened, sacrificing his weight to nullify the attack against them. The exhausted Victini soon fell unconscious, and Valerie let Floaty himself do the honours.
The peace did not last long, however. After Valerie took control of their body her tail slammed down on Ho-Oh's belly, causing her to regurgitate Lugia. Once escaped he devoured the dazed Ho-Oh, and challenged Valerie who was just about to resume feasting. Lugia saved Luxray from the Drilbur who devoured him whole by accident, and after force feeding him, made him his champion in a show he would sit back and watch.
Lugia himself soon grew impatient as Valerie began to gain advantage, devouring the both of them and the region itself. The planet was now no more, leaving him floating in space, as well as Zekrom and Reshiram who had escaped to space too after rescuing the trainers in a vessel ship they found in the ancient city.
Luxray, Floaty and Valerie formed an alliance within Lugia's belly, eating everything that Lugia happened to devour. Once they had eaten their fill they made their escape, and the angry Lugia attempted to counterattack, but Valerie shifted their body in a way that made it difficult to swallow. Then something happened...
Lovers' Luck Out
The Victini they swallowed earlier was fully digested leaving a sphere of immense energy in its place, turning everything in their belly into pure energy in the ensuing pyroclasm. The energy was then instantly absorbed into fat on Floaty and Valerie's shared body, engulfing the rest of them within their folds as well as fattening them to the point their tails came into contact with the sun.
Agreeing with each other that their dinner date had truly begun, they took Luxray along as an ally, and began to feast upon a seemingly endless buffet, moving on from stars to entire galaxies...