The Nazis had different triangle insignias for different prisoners. Red was for political prisoners, yellow for Jews, green for criminals, blue for foreigners, etc. My question is, what if, say, someone was both an anarchist (red triangle) and a trans woman (pink triangle). How would this be displayed?
It largely depended on what a person was imprisoned for. The USHMM discusses that one difficulty in finding how many gay men were killed is that some were arrested under Paragraph 175 but others were arrested as repeat criminals or the Nazi term "asocials" which was signified by a black triangle and covered a wide variety of people. Other than gay men most people in the LGBT community were persecuted as asocials, particularly lesbians or other women who didn't conform to gender and sexual rules. Trans women could have fallen into either group, because they were likely to be seen by the Nazis as gay men they may have been arrested under Paragraph 175 and so marked in concentration or labor camps by the pink triangle. However if they were arrested as political dissidents it is possible that they would have been marked by a red triangle. However because of Nazi views of sexuality a trans woman would be most likely to be arrested as a gay man, or possibly as an "asocial". The main instance where triangles were "mixed" was if a prisoner was Jewish but also imprisoned for another offence, for example a prisoner who was imprisoned both as a Jew and as gay man. However it is also important to note that these identification systems were not altogether standardized within the concentration and labor camp systems. In camps which held primarily Jews, death camps such as Auschwitz II Birkenau, only a yellow star was used. These complex prisoner identification systems were most common to concentration camps within Germany, but were not exclusive to them.
https://encyclopedia.ushmm.org/content/en/article/classification-system-in-nazi-concentration-camps