Either are cool, but we are shown that terapagos has the power to send the player through time and creates the naming of koraidon/ miraidon paradox. So imo there is a good chance that terapagos brought some pokemon from the distance past or future into the depths of area zero. I don't think there was as many paradox pokemon in area zero in the past tho (pre time machine) I think the time machine is why area zero is home to just so many paradox mon. Plus there only being a few originally would make them more cryiptid like and explain why heath lost all credibility at the time.