Premantom is a Kabutops-like fœtus inside a womb- or membrane-like bubble, with a series of other zygotes/membrane bubbles attached to its backside. It bears an umbilical cord despite its calcified appearance.
Premantom, along with Reagain has the highest base Defense stat of all non-legendary Dark-type Pokémon. It also has the highest base Special Defense stat of all Dark-type Pokémon.
Premantom has the highest base stat total of all non-legendary Dark-type Pokémon.
Before the official release of Clover, the shiny form followed the color scheme of its pre-evolution, Embortion rather than being pink.
Premantom is the only Pokémon to have its shiny appearance change within its evolutionary line.
From its new Pokédex entry and cry and its almost Geigue/Metwo-like appearance, Premantom may be based on the theory of Gigyas being based off of an unborn fetus as seen with his true form
The Pokedex entry states, "Others are unable to grasp the true form of its attacks.", in Earthbound when Giygas attacks it says, "You cant grasp the true form of his attacks"
Premantom is based on an aborted embryo. However, the colouration also resembles that of an embryo that has passed away from some form of infection, which results in the undeveloped embryo turning into a white colour. Premantom is also likely to be based on Mew, as they are both based on fetuses and Premantom's shiny form is similar to Mew's shade of pink. It may also be based on a dead baby. Premantom's Pokédex entry is based on Giygas from the MOTHER trilogy, with its cry being sampled from sound effects that play during the battle against Giygas at the climax of Earthbound.
Its name is a combination of "Pre-made" or "Premature" and "Phantom."