The kaiju has not appeared since its titular debut in any other films.
It is often argued that, due to the time travelling and changes in history performed in Godzilla vs. King Ghidorah, Biollante should technically not have existed in the universe featuring Mothra and SpaceGodzilla, and should not then be known to the characters, among other plot holes caused by that particular film. It may be counterargued that the white hole from which SpaceGodzilla emerged in this timeline was linked to a black hole in the universe featuring Biollante. It is most likely merely one of several plot-holes throughout the VS Series chronology. The film also featured a woman whose brother was killed in Godzilla vs. Biollante by Godzilla, featuring stock footage which suggests events happened exactly the same way.
SpaceGodzilla possesses powers similar to those of the original Godzilla, including an oral energy weapon called the Corona Beam and the benefits of Godzilla's seeming near-invincibility. It also possesses psychic powers, most notably telekinesis, and seems to have the ability to home in on Godzilla himself: the creature first lands on Birth Island, where Godzilla and Junior reside. SpaceGodzilla, unlike Godzilla, can power himself by means of crystalline growths which nearly double its size, by which he turns the Fukuoka Tower into a massive energy conduit and often emits EMP-like disruptions. SpaceGodzilla can control its crystal creations telekinetically, using them as projectiles. It can also generate a force field and throw lightning-like attacks from the crystals in its shoulders. Finally, SpaceGodzilla can transform between its grounded, Godzilla-like form and a massive crystalline flying form, providing both defensive and offensive advantage as in its battle with M.O.G.U.E.R.A. in the asteroid belt.
Unlike Godzilla, who in the Heisei series of films is depicted as a force of nature, neither good nor evil, SpaceGodzilla appears to have an element of true malice, as the monster was said by the Cosmos to be headed to Earth for the purpose of defeating Godzilla. Whatever further intentions the monster may have had, if any, are unknown.
Like Biollante upon defeat, SpaceGodzilla's physical body changed into motes of energy and floated skywards. As Biollante was claimed to be immortal, this could mean that SpaceGodzilla may not have died either. (Some fans considered this a hint that Godzilla himself was and technically is in the Millennium series, immortal as well.) To date, SpaceGodzilla has only reappeared in the Trendmasters toyline, and in the videogame Godzilla: Save the Earth.
Godzilla vs. SpaceGodzilla was an older idea that was originally planned to continue the Shōwa series (along with Godzilla vs. the Devil) after Terror of Mechagodzilla, but which had been scrapped. The concept was pulled from obscurity in 1994, following the failure of TriStar Pictures to begin production on a planned Hollywood Godzilla film, which would be another four years in the making. The design was based on an alternate form of Godzilla featured in the 1993 Super NES videogame Super Godzilla; the design was reworked to incorporate crystals into the kaiju's form.
Original versions of the script called for SpaceGodzilla to face Godzilla and a second Mechagodzilla, a plan scrapped when it was realized that against the combined might of Godzilla and the machine which very nearly killed him the previous year would make the battle too one-sided. Instead, the less-powerful Moguera was revived and updated for this purpose.
SpaceGodzilla's only other appearance is in the game Godzilla: Save the Earth. One of the last hidden monsters unlockable, SpaceGodzilla is a very strong weaponry-oriented combatant. Able to call up crystal towers to speed his energy recharge rate (which otherwise recharges very slowly), SpaceGodzilla can use a variety of energy and missile-based attacks, from crystal shards, slamming his foe with a large chunk of crystal, making the towers fire energy bolts at the foe to his powerful Corona Beam. SpaceGodzilla also uses energy in many of his melee attacks, and especially in his grabs and throws, levitating opponents and buildings into the air and flinging them with his mind. SpaceGodzilla is as tough defensively as Destoroyah, making him a powerful and difficult monster to defeat. He replaces Orga as the final opponent in Hard mode.