The ShodaiBara's name comes from shodai (初代?), meaning first generation, and Bara, which comes from Baragon's Japanese name, Baragon (バラゴン?).
The ShodaiBara suit had bat-like ears, skinny arms, bulky legs, and an armored back. In Destroy All Monsters, the suit was painted darker and the entire head had to be removed because it was overused and a new one had to be made. The new head had different ears, less teeth and different eyes.
The ShodaiBara suit was originally supposed to be in more scenes in Destroy All Monsters, but the suit was overused when Eiji Tsuburaya used it for Ultra Q and Ultraman, the suit was first used for Pagos in Ultra Q episode 18, then it was used for Neronga in Ultraman episode 3, then it was used for Gabora in Ultraman episode 9, and finally, it was used for Magular in Ultraman episode 8 (it is very likely that episode 9 was made before episode 8). When Tsuburaya returned the suit to Toho, it becomes very clear that they weren't able to use the suit that much which explains why the suit was used at the very end of the movie when it shows all the monsters living peacefully on Monsterland.
Despite Baragon's supposed height in the films, the ShodaiBara costume is roughly at equal height/length compared to both Godzilla and Gorosaurus.
The ShodaiBara suit's wireframe skull would be later used as the base for the Flying Hedorahprop.