I'm surprised the press release states Rose and not Rosé. Why the creators Akira Toriyama/Toyotarou would explicitly state Rosé in a Q&A? I have no idea. And the short story behind this character is that this character doesn't even belong in Dragonball Z. This character is instead in the current show, Dragonball Super, which takes place MOSTLY after Dragonball Z (but before the ending of Dragonball Z, as the ending had a timeskip). And the trailer is trying to reference that fight between Future Trunks and Goku Black, as that was an actual story arc in Dragonball Super.

SSGSS Goku/Vegeta (also known as Super Saiyan Blue) are also from Dragonball Super. Once again, for the sake of fanservice, we are having characters that aren't even from Dragonball Z, which I'm pretty sure Dragonball Z was the original intention of Arc System Works/Bandai Namco Entertainment.