Following on from Teod53's excellent groundwork...
I'm thinking that Cottonee/Monmen might be the answer, as although it doesn't seem to mean "many men" in Japanese, the Japanese name does sound a bit like many men in English... Perhaps the quiz writer made an error, or perhaps they meant "sounds like" instead of "means"!?? I would say that from Teod53's shortlist, this is the best contender. Also it is odd, as the Japanese names for Pokémon are usually related to the Pokémon in a similar way to the English names. I would expect a Pokémon called "many men" in Japanese to represent, well, many men! Or at least, to have multiple heads, or something...
I've written the Pokémon names as English = Japanese/Romanised Japanese ... I got the info from Bulbapedia, hope it helps!
Shelmet = チョボマキ Chobomaki: Chobomaki may be a combination of おちょぼ口 ochoboguchi (puckered-up mouth) and 巻き maki (to coil or roll).
Mincinno = チラーミィ Chillarmy: Chillarmy is a combination of chinchilla and charm.
Cottonee = モンメン Monmen: Monmen is a corruption of 木綿 momen (cotton).
Munna = ムンナ Munna: Munna may be a combination of moon, ムシャムシャ mushamusha (onomatopoeia for eating, as it eats dreams), or 夢想 musō (dream), and luna (Latin for moon), or 花 hana (flower).
Snorunt = ユキワラシ Yukiwarashi: Yukiwarashi may be a combination of 雪 yuki (snow) and 座敷童子 zashiki warashi (a spiritual creature found in the folklore of Iwate Prefecture).
Skitty = エネコ Eneco: Eneco is a combination of 狗尾草 enokorogusa (foxtail grass, a type of plant that Skitty's tail resembles) and 猫 neko (cat).
Kirlia = キルリア Kirlia: Kirlia is derived from Kirlian photography, a special way of taking pictures that supposedly reveals psychic energy auras around subjects.
Vulpix = ロコン Rokon: Rokon may be a combination of 六 roku (six) and 恨 kon (grudge), which refers to the curse that Vulpix and Ninetales may cast on their foes. This is also reflected in Vulpix, which learns Grudge. Kon may also refer to the Japanese onomatopoeia kon kon, which is the sound that foxes make. Furthermore, a コンロ konro is a gas burner stove. Also, an alternate reading of the Japanese word for fox, 狐 kitsune, is ko.
So, none of these Pokémon seem to mean "many men" in Japanese. I also tried looking up the meanings of other Pokémon who looked like they had multiple personalities e.g. Exeggcute, Dugtrio, Dodrio but they weren't close either and don't fit the other descriptors. I would go with Cottonee as my best guess. What's the quiz for? :)
Again credit to Toed53 for doing the hard work and making the original shortlist.