Since the games’ release, there has been one stage that’s never been playable in versus mode in both Marvel vs. Capcom 3 and Ultimate Marvel vs. Capcom 3: final boss Galactus’ stage. However, the release of the PC version has since brought hope–thanks to the ability to apply mods to that version.
In the video below, Spook Toque demonstrates a mod that allows Galactus’ stage to be playable in versus and training modes. Take note, however, that the mod isn’t perfect–there are more than a few issues with it, such as the ground lighting not being correct. That said, the stage mod itself does work despite these issues, replacing the Training Room stage in the select screen.
Interested players can download the mod here.
Source: Spook Toque