Most characters are canonically pansexual including the Champion, as a writer convenience. You can mentally roleplay them otherwise depending on how you imagine your Champ sexually and physically but the writing is going to assume that the Champ is attracted to everyone sexable regardless of their physiology and for the most part the NPCs are the same with regard to the Champ. There are only a few characters who are strictly interested in one type of character or another. Offhand Jin-Jin is only interested in males, Lusamine and Gwyn are only interested in Champs with a penis (likewise Kiyoko for her sex content), Garret and Janeen are only interested in Champs with a vagina.