Is there still a technical definition for legendary/mythical?

Until Generation 7, all legendaries and mythicals had no evolution families and BSTs of 580 or greater. For whatever reason, Game Freak decided to be extra liberal this time by introducing the Tapus, which have BSTs of 570, and introducing Solgaleo and Lunala, which have evolution families. The most logical approach I could think of is to change the definition to the following. A Pokemon is legendary or mythical if and only if:no Pokemon in its evolution family can hatch from an egg laid by a Pokemonits BST is 570 or greaterHowever, this definition would include Silvally and the Ultra Beasts. Can somebody think of a better definition? Is Silvally a legendary now?

Pleaselog inorregisterto add a comment.

Well first of all, mythical Pokémon are way different, though most legendaries are mythical.

Legendary: Well, ever sense Cosmog and its evolutions, it really changed the idea for them. Quoting Bulbapedia: “no Legendary Pokémon can breed or hatch from an Egg.” which is true about Cosmog. Though the fact Cosmog can evolve and can be found twice, can both be explained with reasoning. For evolution, it does state that Cosmog is legendary quoted by Bulbapedia: “Cosmog is a Psychic-type Legendary Pokémon introduced in Pokémon Sun and Moon.” Only one copy of the legendary Pokémon exist in each game, but Cosmog has two of them, and this is where my theorist side came out. The reason why is because of one simple answer. The reason is the two evolutions of Cosmoem, Solgaleo and Lunala. The truth is for this is that they don’t exist until you find another Cosmog. That last Cosmog is only there to restore the missing legendary, the one you can’t get.

Mythical: It turns out, from the data I gathered, the Tapus are actually not mythical. Because its not a legendary or mythical Pokémon, it is just like Ultra Beasts. It’s it own category. This also explains why Ultra Beasts aren’t legendaries.

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