Board Thread:General Discussion/@comment-25156739-20150914163822/@comment-38952966-20200828063741

If GER can activate in Diavolo's erased time, I think it's reasonable to assume it can activate in stopped time as well, even if we can't say it for certain. And I'm relatively certain GER activates automatically to protect Giorno.

As far as I can find, there's no interview with Araki saying that Star Platinum is the most powerful Stand. What I could find was Araki saying that the only way to beat Jotaro was to remove or disrupt his time stop, which GER may or may not be able to do.