In the past few days, there have been a lot of discussion about the “Monster Trio”. From the defense of Sanji’s fans: “Monster Trio will never change”, to the other side: “Luffy, Zoro, and Jinbe are the new Monster Trio”, or the middle ground “Luffy is not in Monster Trio, it gonna be Zoro, Sanji, and Jinbe”. But I’m not here to discuss that.
One comment I constantly seeing got brought up is that “Monster Trio is a made-up term by fans, it’s not real”. This is FALSE (or at least not in the way you think).
If you checked the Japanese RAWS, there have been 2 instances where Oda used this “term” in the manga:
Chapter 455 – Thriller Bark
Chapter 606 – Fishman Island
Both Nami and Caribou used these Kanji words: 怪物3人組 – which literally means The Three Monsters (or Monster Trio as fans are used to now).
I think the obvious reason people think it was made-up is that back in the day, the official English translation never translated it as “Monster Trio/Three Monster” or something directly like that, only using something more indirect like “the three strongest guys” (by Nami), “those three strong fools” (by Caribou).
In contrast, the Weakling Trio – 弱少トリオ was used by Ussop back when they reunited on Sabaody after Time-Skip. This is even more directly because トリオ literally means Trio.
Chapter 598 – Return to Sabaody