Reading game's pokedex, documentation, bulbapedia, serebii and other credible scientfic sources I cannot find any data that backs up my theory, but I think there may be some kind of correlation between ancient and future pokemon with previous pokemon.

Some things that may back up my claim:

1) Koraidon/Miraidon are side to be past and future forms of Cyclizar (in the game)
2) The game points that Great Tusk and Iron Treads highly resembles a Donphan, and one of the characters in the last quest thinks Scream Tail is a Jigglypuff.
3) Most of the pokemon have a high resemblance to common pokemon, I'll list them:

Great Tusk, Iron Treads -> Donphan
Brute Bonnet -> Amoonguss
Sandy Shocks -> Magneton
Scream Tail -> Jigglypuff
Flutter Mane -> Misdreavous
Slither Wing, Iron Moth -> Maybe Volcarona
Roaring Moon -> Mega Salamence
Iron Hands - >Hariyama
Iron Jugulis -> Hydreigon
Iron Thorns -> Tyranitar
Iron Bundle -> Delibird
Iron Valiant -> Gallade

I know about the great dangers "pattern recognition" posseses, and I'm usually skeptic about conspiracy theories but these similarities seem to be too much for a coincidence.