>>38412279>I'm talking in terms of realism, mostly.This is an equally interesting, but autistic point of discussion: as all good in-depth Pokemon topics are.
There seems to be two general defining distinction separating the legendary Pokemon from one another: Ones that are basically GODS or otherwise deified beings due to how powerful and in turn the influence they had on primitive society and developing culture. God'mons are exceedingly rare- we're talking maybe single digit numbers, they may even be immortal or perhaps Arceus just makes more? You're obviously not going to see trainers using God'mons unless there's >game mechanics< afoot or some rare circumstance going on.. Like when Rayquaza went up to space to fug Deoxys.
Ho-Oh, Luigia, Rayquaza, Groudon, Kyogre, Dialga, Celebi, Palkia, Giratina, Darkrai, Cresselia, Regigigas, etc.. etc.. Are almost assuredly one of a kind Pokemon. There's too many legendaries, I'm not gonna list um' all.
The second are just legendaries that are considered 'legendary' merely because they're exceedingly rare, but are otherwise just 'another' Pokemon. Most of their folklore or cultural significance stemming from their rarity or what have you.
Zapdos, Moltres, Articuno, Entei, Suicune, Raikou, The Gigas, Latias & Latios, Cosmog, and Heatren are most likely just 'super' rare.
Gray area kind of exists with the genetically engineered weapon'mons like Silvally and Mewtwo, because while they're also super rare and legendary.. More of them could -hypothetically- be made. I know Aether keeps producing Type:Nulls and there's maybe 3 Mewtwo in existence? Mewtwo can also probably breed with Mew, so who knows.
MEW is also a weird exception because Mew is only rare because it's a living fossil kind of progenitor species: it bred, spread across the world(s), speciated into thousands of species of Pokemon, and is now a legend because it did such a good job of evolvin' itself to extinction.
