Chopper may seem like a cute mascot for the One Piece series, yet he shouldn't be underestimated by fans.
The reindeer doctor is typically grouped with Nami and Usopp as part of the Weakling Trio. With that said, Chopper is a very capable fighter. His years of medical expertise have been put to good practice in One Piece.
With the use of his Hito Hito no Mi, Chopper is able to transform into a reindeer-human hybrid. He can also use Rumble Balls for additional forms. Throughout the One Piece series, Chopper has proven to be a physically strong combatant. His bounty of 100 bellies is a very inaccurate take on his threat level.
Note: This article contains spoilers from the manga.
One Piece characters that Chopper can defeat
Usopp is a crafty sniper who can use Pop Greens to great effect. His plant monsters would certainly give Chopper some trouble. Usopp is also extremely resilient, as shown in the Onigashima Raid. Ulti managed to crack his skull with a headbutt, yet he kept on going.
With that said, Chopper's Monster Point is too physically dominant. During the aforementioned raid, Chopper managed to slightly injure Queen of the Beasts Pirates, a pirate with a bounty over the billions. Usopp wouldn't last very long under a similar thrashing.
3) The Funk Brothers
The Dressrosa colosseum battles introduced these brothers in the C block. It was directly stated that Kelly took out a pirate with a bounty of over 100,000,000 bellies. That is somewhat impressive for a low ranked fighter.
Kelly can use the Jake Jake no Mi, a Devil Fruit that seems fairly useless at first glance. He can turn into a jacket and be worn by others, like his brother Bobby. However, Kelly also gains the wearer's powers, such as their physical strength and stamina. This makes the Funk Brothers a force to be reckoned with.
Nonetheless, Chopper has experience fighting master assassins. He managed to defeat Kumadori of CP9 back in Enies Lobby, and that was before the One Piece timeskip. Chopper would take a physical beating here, but he definitely has the pain tolerance to outlast the Funk Brothers.
2) Galdino (Mr. 3)
A former agent of Baroque Works, Galdino gave the Straw Hats trouble back in Little Garden. His Doru Doru no Mi allows him to control large amounts of wax. Galdino can not only trap his enemies, he can also make wax clones of himself for the purpose of confusion.
Of course, Chopper can easily sniff out the real Galdino with his heightened animal senses. He is also physically stronger after the One Piece timeskip, whereas Galdino is still at the same level.
Chopper could use a combination of speed and strength to quickly take care of him. If need be, he can also dig underground to avoid hot wax. Both of these One Piece characters are very intelligent, yet Chopper has the physical advantage. Galdino would have to stall for most of the match.
Wapol is an early One Piece villain who debuted on Drum Island, the same arc where Chopper showed up. He can use the Baku Baku no Mi to eat anything and merge with their properties. For instance, Wapol can try to swallow his opponents or hit them with a tongue cannon.
At this point in the One Piece story, Chopper can find a way past Wapol's defenses. His additional forms could be very useful here, such as Guard Point for cannonball attacks. Wapol would likely get destroyed by Kung Fu Point, which grants Chopper martial arts skills.
One Piece characters that Chopper cannot defeat
Nami isn't a physically strong fighter by One Piece standards. However, she does have a powerful weapon at her disposal. Since the events of the Onigashima Raid, Zeus is under full control of Nami. This thundercloud is blindingly fast and can even take out the likes of Ulti.
Chopper doesn't have the agility to dodge lightning attacks from Zeus. Nami should have this One Piece fight in the bag. Zeus is a very powerful weapon that can overwhelm weaker enemies.
3) Caesar Clown
This mad scientist was a dangerous threat back in Punk Hazard. With the aptly named Gasu Gasu no Mi, he is able to control various gasses at will.
Without enough prep time, Chopper would likely have the knowledge to counteract these attacks. However, without proficient use of Haki, he cannot bypass Logia intangibility. Chopper's Monster Point would be useless in this fight.
Caesar may seem like a joke villain in One Piece, yet he can knock out weaker opponents in an instant. He did so to Franky and Nico Robin back in the Punk Hazard arc, and they are considerably stronger than Chopper.
2) Vinsmoke Reiju
Reiju is a genetically modified soldier with access to poisonous attacks. The princess of Germa Kingdom often combines her physical attacks with toxic substances, as seen against Smoothie in Whole Cake Island.
Chopper definitely has the medical expertise to survive her poison. Unfortunately, Reiju also has a very hard exoskeleton. She would give the good doctor a very hard time with her combat prowess. Reiju is faster, stronger, and more dangerous in a direct confrontation.
Chopper had already fought Queen during the Onigashima Raid. Not only did he find a cure for Queen's destructive viruses, he also drew blood from the Beasts Pirate. Chopper's Monster Point is arguably his strongest form.
Sadly, it's later revealed that Queen was purposely toying with Chopper. He was barely even trying in his brief skirmish with the doctor. Queen is goofy by One Piece standards, yet he is also a skilled engineer and scientist. He gave himself a very powerful body via cyborg enhancements.
Chopper doesn't have the means of putting down Queen for good. Meanwhile, the latter could use laser beams or Germa 66 techniques. He can even use invisibility for an unfair advantage. Queen is far above Chopper's current power level.
Note: This article reflects the writer's personal views.