In all of my conlangs this far, plurals have not distinguished gender on the morphosyntactical level (i.e. there's just "they", not a masculine-they and a feminine-they). The morphemes that form the plural nouns may well be somewhat gender-specific (but mostly in the nominative and possibly some other additional case), but syntactically, the languages don't care about gender once plurals are used.
In real languages, there are loads of languages that operate like that, but there's also languages that operate in a different way, and do distinguish plurals of feminines from plurals of masculines (or even greater systems). Sometimes, greater numbers of genders have some distinctions be conflated in the plural.
However, I was thinking of something that might exist in the world, but which I would be surprised if it does. For the sake of simplicity, I'll stick to a two-gender system: masculine and feminine.
Let's have three plural markers: masculine, mixed and feminine.
Now, consider a noun, and a noun for which we sometimes might have mixed-gender plurals. Let's go for, say, "person". Now, "male person" is obviously "man", and "female person" is "woman", so let's go for these words.
Now man+masc.plur means "men", man+mixed = "persons". Woman+fem.plur = women, women+mixed = "persons".
"Mixed" plurals are referred to by the pronouns of the gender of the lexeme onto which the suffix is added, so "man+mixed" would get the masculine pronoun.
Now for the twists: some words lack forms! Some words use the other gender's root with the three suffixes. Some words have a separate suppletive root for one, two or all three of these. Some words just cross the lines: the masculine plural of "shaman" is based on the feminine root, and the feminine plural is based on the masculine root (this might be to confuse evil spirits). On some words, the morphemes are out of whack - "mixed" might mean either feminine or mixed, or masculine or mixed, depending on the lexeme. And finally, for some nouns, the "regular" suffix might also include the mixed meaning, while the "mixed" morpheme is not used at all.