We have a large and unwieldy crossover ships section in the tagset. To help with selecting your requests or offers, we have a searchable spreadsheet here. You can search the crossover ships in the tagset by fandom or by character. (Note that your searches will be visible to everyone with the link unless you save yourself a private copy of the spreadsheet.)

Many thanks to mornelithe_falconsbane for providing the code to make the spreadsheet searchable!