Pokemon Fighting types are a staple, having existed in the franchise since its inception. Fighting Pokemon are typically strong and based on martial artists. Most of their moves tend to be in the Physical category, which makes sense as a Fighting archetype. They are also one of the best offensive types, with their moves being super-effective against five other types.
Pokemon can have a second type as well as their original type. This allows Pokemon trainers to offset any weaknesses specific Pokemon of theirs have, as well as open up available moves in their moves pool. There are many great secondary types for Fighting, with some being better than others to use on the popular turn-based RPGs. When adding any secondary type, players should consider the weaknesses and strengths and how this will change a Pokemon's competitive ability in the arena.
7 Dark
Dark can be a good choice as a secondary for Fighting-type Pokemon. It adds immunity against Psychic, which helps to offset Fighting 'mons natural weakness to the Psychic-type. It adds resistance to the Rock, Ghost, and Dark types which adds better defensive type coverage.
However, the Dark-type as a secondary does open up Fighting, Flying, and Fairy as weaknesses. Players must make sure that if they are adding Dark as a secondary type that they consider the battle party of their opponents. Dark Pokemon are some of the strongest, however, so there are great moves that can be utilized through adding this typing. A good example of a Fighting/Dark Pokemon is Pangoro.
6 Bug
A good secondary type choice for Fighting-type Pokemon is the Bug-type. This does add a weakness to Fire, Flying, and Rock-type Pokemon but it adds an advantage over Grass, Psychic, and Dark Pokemon. While purely Bug Pokemon can be fairly weak, they can complement a naturally-strong type such as Fighting well.
Players that are looking to add Bug as their secondary type should consider the weaknesses this could add and weigh them up against the benefits. Bug Pokemon are underrated, and they possess some very good moves that can be utilized when making Bug a secondary type.
5 Psychic
Psychic is a good secondary-type for fighting Pokemon as it stops opponents' Psychic moves from being super effective. It will still be weak to Flying and adds a weakness to Ghost, but Fighting and Psychic have most bases covered when it comes to type coverage.
Fighting benefits Psychic because otherwise super-effective Dark and Bug moves do normal damage. After all, Fighting resists them. A good example of this principle in play would be in the Pokemon Medicham. By using Psychic as a secondary type, it opens up Pokemon to the best Psychic moves.
4 Steel
Steel is a great secondary-type for Fighting Pokemon due to the resistance it offers. With this as a secondary-type, both Flying and Psychic are no longer super effective, while previously super-effective Fairy moves have no effect.
Steel does however give a weakness to Fighting, Ground, and Fire instead. Lucario is a great example of this. This opens up moves from the best Steel-type Pokemon to the move pool. Players who want to give their Fighting 'mons a resistance to various types while focusing on offensive power should go for Steel as a secondary type.
3 Electric
The Electric-type only has a weakness to Ground, meaning most of the time it's going to help more than harm as a secondary type. It resists both Electric and Steel moves and removes the Fighting type's weakness to Flying.
Electric does, however, give the weakness to Ground. Players looking to add the Electric secondary type to their Fighting Pokemon will find that they benefit more than they lose from it, and have good type coverage against the other types available. This opens 'mons up to the best electric moves.
2 Rock
While using the Rock-type as a secondary type will gain the weaknesses of Ground, Water, Grass, Fighting, and Steel, it remains a great offensive secondary type choice for Fighting Pokemon. It gives good type coverage, giving super effective Same Type Attack Bonus against a good number of types including Steel and Flying.
Rock Pokemon are some of the toughest around, and Terrakion is a great example of a Pokemon that combines both Fighting and Rock to be deadly offensively, even if being a little weak in terms of defensive capabilities.
1 Nothing
While a lot of players like to add secondary typings to their 'mons, sometimes it's best not to add one at all. With Fighting, players can be assured that there are only two weaknesses to Flying and Psychic, which is pretty good-going when compared to the other types.
There is only one STAB type, so coverage is limited, and Fighting moves have 0 effects on Ghost types. Despite this, players know where they stand with pure-Fighting types and don't run the risk of adding extra weaknesses to other types that could prove troublesome when fighting.