>>56792087They’re pokemon sent across time by Terapagos. The crystals have the power to send things across timespace temporarily, like we see in Kitakami with the professor; the ones Heath saw were only temporary, hence why nobody could find them again. The professor’s machine could harness the power of the crystals to send them over permanently via pokeballs though.
Same thing happens with the raid dens- if you don’t capture the pokemon summoned by the crystals they disappear across timespace again.
