For 4U, the Seregios, Shagaru Magala, and Gogmazios are respectively nicknamed Steve, Stephenson, and George. When the Seregios's name was completely unknown, someone asked one of the Capcom employees what it's name was. They jokingly replied to refer to it as "Steve", and it spiralled on for Stephenson and George as well.
Also, unless you have custom firmware or a (friend with a) Japanese copy of the game, you can't get some of the extra goodies that come from Japanese-only download quests for the Freedom games. Some are joke items like a giant stuffed animal Hammer (Polytan) while others, like the Jolly Roger set, are quite useful.
Reversed in Monster Hunter Tri, in which you can get three exclusive fan-designed weapons only in the international version of the game. And the WiiSpeak support for online play.
Any event items in the game that aren't the same between regions each have a Japanese and a foreign variant. While the two versions are different in appearance, they have the exact same stats. For example, the Pirate AxeJ has the exact same stats as the Sinister Saints.
What Could Have Been: Some of the monsters in 3 Ultimate went through different names during the localization process.
Arzuros was derived from azure and ursus, resulting in various Punny Names before they could settle on the final spelling.
"Zeograth" was considered for Zinogre at one point, being a combination of Zeus and wrath. However, because Zinogre's name already appeared on some merchandise in English, the director requested that its name stay Zinogre.
The Stygian Zinogre's initial name was "Scarlet Zinogre", but the Japanese development team wanted its name to have more emphasis on its Hellhound appearance.
The translators wanted to call the Purple Ludroth "Purple Royal Ludroth", but the maximum length a monster's name can be was 16 characters, so they had to drop the "Royal" part.
The Baleful Gigginox's initial name was "Copper Gigginox" due to its normal skin color, but the dev team wanted to emphasize its electrical attacks.
"Rouge Qurupeco" was considered for Crimson Qurupeco at one point, but due to how easy it was to mix up "rouge" with "rogue", they decided to stick with crimson.