>Google translator:
Not hard to understand, anon. Legendary / Mythical Pokémon can produce totally different species. What prevents them from reproducing without sexual partners?
> First theory: At some point there was an original Lugia, which produced the original trio. Then they reproduced and continued the cycle.
> Second theory: at some point there was an original Lugia, which spawned the original trio. Lugia reproduced another Lugia, who produced his own trio. The cycle repeated itself indefinitely.
> Third theory: union of the two previous theories.
L / M Pokémon take a long time to make these reproductions / productions, making the species very rare. Each has a role in the Pokémon world, and its reproduction depends on its importance. Arceus is unique because it is the pokemon god. Groudon is unique because he created the lands, Kyogre because he created the seas, and Rayquasa for a similar reason. Moreover, the history of these three Pokémon to no evidence of duplicates. However, they have already shown more than one Lugia / Latios / Latias / Articuno / Zapdos / Moltres and others in the anime and other media.