Before the game starts:
Dragora, Black Dragon of Void and Chaos:
Billions of years ago, nothing was in existence. No, seriously, nothing. All that existed at the point was a black void; The home of the great chaos dragon Dragora. With near limitless power over the universe, it could do things however it pleased. However, Dragora was gaining power too fast for it's own good, and was forced to vomit up the particles of the universe not only enough for one universe, but TWO of them. In the process, Dragora's original form was forever lost and now looks no different from the black holes all other creatures would fear. Dragora's deed of losing power done, it hides away at the center of the universe in an endless void where it remains undisturbed to this day...

Terranadrosus, Great Ice Spider of Death and Fate:
In the Carboniferous, only four types of creatures existed; The Fish that ruled the seas unopposed, the Amphibians that were masters of the rivers and lakes, the Arthropods that had won first place in the line of evolution, and finally the Reptiles, a nomadic type of animal that will forever be remembered to this day. However, three spirits who had yet to come into existence foretold that an entirely unknown class called the Mammals shall rule the planet one day, and that the only other place the Reptiles will rule anymore will be the other universe; The Zauridon Universe. With that in mind, several groups of each class of animal at that time traveled all the way to the South Pole of that time period, where they were greeted with the great tree where there was otherwise no life at all; Yggdrasil. In this tree lived at the time the most massive lifeform to have evolved yet; Terranadrosus, a mysterious, Spider-like creature that ruled over the massive tree of life. Terranadrosus agreed to severe the connection between the two universes, only under the promise that one day two beings would face her in battle, but for now it seemed nothing was powerful enough to take her down yet. They all agreed to the promise, and many species and individuals were transported to the new world, all of which would be succeeded by their own Zauridon ancestors, if not become Zauridons themselves right away...

Grandis, Master of the House:
1994, an infant that would be known as Marty is born and had an imagination that was almost entirely unmatched for anything else to have ever existed at that point. So great was his imagination in that his own birth had awoken and caught the attention of the great Dragora, who seemed very interested in the infant. The three spirits, one of Sky, Land, and Sea, each questioned the idea of a human being the one to rule over the Zauridons, but nevertheless Dragora ignored the three entirely, for even at that point they still did not exist yet. In preparation for the tests that Dragora would give to Marty, he had ordered the mining of a rare metal alloy that would make it's wearer the most powerful being to ever exist.
Years would pass as Marty matures from an infant to a 14 year old in 2008, where Marty's imagination had peaked. This, however, was the last time Marty was genuinely happy with his life. For nearly 10 years though, his imagination had led him to discover the Zauridon Realm much earlier than anybody else, and thus ended up with the bird-like Glidosaur as his starter. He and Glido, the name he had chosen for the Zauridon when he was only 6 years old, had made it past long challenges already at this point, especially given how Glido was nothing more than an imaginary friend at this point. All of that, everything they had known up to that point, was about to change. Big time.
In 2009, the three spirits contacted Marty and challenged him to a great battle, one that they were sure he wouldn't win. Nevertheless, Marty found his way to beat the three spirits, such as his imagination giving the three physical forms to hit and also giving Glido an upgraded form that would be known as Qdrasaur. Obtaining both Hardheadasaur and Spinersuchus as allies to his journey, where he ultimately arrived in the Zauridon Realm and destroyed the three spirits out of his own rage and angst of that time. Dragora is the first to greet Marty after his victory in the tests, but it's a bit of a harsh greeting in return as Marty forcefully claims the armor that Dragora had worked to build. While Dragora had intended the armor being able to be controlled by itself, he was surprised that this armor, normally unable to control in every way, was perfectly controlled by Marty and nobody else. With this, Marty decided it was time for a few changes here and now, but he decided now was not that time as he got used to his new looks. The name Marty, to him at least, was only a mere memory of who he was; A tale meant to be long forgotten and disposed of. His name at that point would be known as Grandis, the unstoppable, imposing master of the universe, and something that every Zauridon should rightfully both fear and respect at all costs...

-Alienasaur requires every quest up to that point having been accomplished. No specific amount of Zauridons required, just clear the quests and beat Alienasaur as the final boss. Alienasaur is Level 65.
-Emperius's quest requires the defeat of Alienasaur AND obtaining it as well, which Alienasaur has to be Level 65. After revisiting an important location from the plot you've been to already before, you'll find the place in ruins and a new area is opened up, inside are Alienasaur as common enemies on the final floor and at the very end a Level 77 Emperius.
-Terranadrosus's quest is unlocked by obtaining 17 of the Zauridons in the game, meaning every non-Legendary in Gen I, in addition to obtaining Emperius and training it to Level 80. It's dungeon is actually part of an older one that couldn't have been accessed before at the time, but the barrier blocking it was now completely demolished. At the end, you'll encounter three Emperius...... Only for them to be torn apart by Terranadrosus, which is Level 85.
-Dragora's quest is unlocked after obtaining Terranadrosus and training it to Level 88, and obtaining 23 of the Zauridons obtained at that point. Afterwards you'll hear of a mysterious portal being opened. Dragora will explain each of whole backstory of the reason this universe exists, and will hint at the final Zauridon of that Generation, but after it's defeated, you'll have access to a new area, but this one far north.
-Grandis's quest is the 100% completion quest in the game. As such, the 24 Zauridons before him must all have been obtained AND all trained to Level 100. The latter is easy because half of Grandis's area is unlocked, and in it you face Zauridons that give tons of Exp, boosted by the fact the area itself boosts Exp yields of the Zauridons, but ONLY at certain levels for the party's combined level, increasing the higher level you are. All the opponents are either the Five Upgraded Starters, Hipickosaur and Triterrasaur, or Alienasaur. Note this is the only other way to obtain the Upgraded forms outside of trading, so Eggs dropped from the ones here can be used to trade with others. After these requirements are met, the final Level Barrier of 2400 will break and take you to the final area in the game, where upon finding a lone house you'll be swarmed by multiple waves of powerful Zauridons all at Level 100. After these waves, you'll face Grandis as well. He CANNOT be damaged unless your party Zauridons are Emperius, Terranadrosus, and Dragora, but Grandis is also capable of easily demolishing all three by himself because all of his attacks hit the entire party and have insane damage. After defeating Grandis, you'll unlock the final cutscene ending and the credits will role, afterwards you are teleported back to the beginning town in the game, with the G-Armor needed to obtain Grandis.