>>51036213I know the question was likely for Super, but in Explorers' case, there's 3 different partner "personality" scripts, standard boy, girl, and alt boy. Most starters default to the boy script (he says "Let's do it! No excuses!" in boss fights, and in the JP version, talks with the "boku" pronoun), while the girl starters obviously pull from the girl script (who uses "watashi", and most story "what?" lines turn into "pardon?" instead). The alt type is used for certain male starters like Munchlax, and instead refers to himself with "oira" over boku.
If you mod in custom starters, they'll always default to the "boku"/standard boy script.
Of course, there's also the gameplay differences male/female mons offer in Explorers too, with boys having slightly better crit, while girls have the accuracy evasion buff.
For Super though, it only really changes whether the partner says "boku" or "watashi", with the female partner having a mirrored portrait when looking through your teammates list.