Main problem of Red Card is that, when you're OHKOed, it doesn't activate. I didn't see it mentionned in the previous pages, but it's worth to note, as it changes a lot of thing against setup sweepers. It's not in the object description (but as no effect of rapid spin when using kill user), and it might be a showdown bug, but in fact it actually limits effectiveness of Red Card's variant. Testing Deo-D to have a less theoric opinion, I faced one time a +4 Latias and another a +6 under a sub Terrakion. Even if I managed to win these match (and once these boosted threats were removed, the full layers I had set probably helped), I was let in a much worse situation than I thought being when using Red Card, forced to sacrifice a pokemon in order to force them out.