And by minor I mean characters who didn't necessarily have a huge impact on the series, but were important during their arc. For me,
Shushu the dog being choked
Back when I first started reading One Piece, this was the first character who gave me feels, moku. He was an extremely courageous animal who kept fighting and fighting to protect what was important to him, even standing up to a lion. What I like most about characters like this is how weak they are, but how brave they can be to protect something, moku. An extremely wise choice of character to relay feelings with, and I was really glad to see he even survived the time skip.
I loved this guy during the Skypea arch. He had substance, an interesting background and a cool fighting style. His design was awesome too, and how much damage he could take for someone of his tier.
She was pretty cool.She had a strong ambition even though she was weak, similar to Shushu and bought out the serious, more deeper side of Luffy, moku.