>>51762435>They're kinda like how Wiglett is to DiglettNot really. As many say before, they are convergent evolution, two completely different animals that so happen to appear similar only to adapt and survive in the environment they are born in. That's Wiglett and Diglett
Paradox is supposed to be the same Pokémon species just place out of time. They also show what the Pokémon look like before their current state or after. Take the Volcarona line, Past is supposed to be what they were before they evolve and gain wings while the Future is supposed to be them more machine than organic. As you said already, they have different number and name. From what we can gather, the Future Gallade or Kirlia is meant to be the converging of both Gardevoir and Gallade where there is no point of have a split evolution and it loses its psychic power to have its fighting and fairy typing meet as one to create what Gardevoir and Gallade breeding will lead to in the future.