Rape is specificly mentioned in the u18chan guide under misc. "For any extreme kink images containing guro, non-consensual, rape, scat, violence, vore, watersports, drug use, etc, regardless of other content.". While drug use, non-consentual, water sports, and most extreme kinks are not enforced to be here (moved here when posted else where) rape, vore, violence during sex, waste play (scat, piss, etc) are forced to be here.
Though many comics on non-basment boards may contain non-consentual/rape wether or not it gets moved here depends on how graphic it is. If the raped character is visibly crying, or if such action has visible affect on them emotionaly/psychologicly, or if there be any blood/ injury/ disformidy/ death caused it will be moved to gore.
Despite stuff existing on other boards, its safer to post it here. There are no wrighten guidlines on when extent of material deemed to be gore by the u18chan guide can be posted on other boards, its completly sugestive. But if something is too graphic it may result in punishment to the poster. So posting it in gore is the safest option.