So, what is the Fighting-type?
All JRPGs have physically oriented classes, some of which exclusively work on physical moves. Classes like warriors, paladins, monks and whathaveyou. Some of these groups can also appear as enemies, and that's precisely what Fighting-type in Pokémon is. Because physically oriented classes are "evergreen" classes, that is, classes that can be used in any part of the game, Fighting-type had to be one of the most versatile and balanced types in the game. But since Pokémon has imperfect balance, perfect balance means overbalancing.
Fighting-type is also heavily influenced by association of martial arts with philosophy, and the association of chi with martial arts. This has allowed Fighting-type to be a de-facto Earth type, and due to the fact that it was the largest type in Gen I of Rock, Ground, Fighting triumvirate, this made Fighting-type the poster boy of Earth types in TCG, and this remains to be so to this day.
The History of the Fighting-type:
First generation of Fighting-type was interesting to be sure. Fighting has appeared in both early game, mid-game and late-game. In its initial conception, it was more closely associated with Ground and Rock-types, and this association continues to this day. However, most interestingly, Fighting-type had two type experts, Kiyo, the former Gym Leader of Saffron City, and Bruno of Elite Four. Despite this, Fighting-type was not granted its own "dungeon", whereas all other types had their own specific regions. Fighting-type also had better Special than Rock, Ground types, but not by much.
However, Fighting-type was not as powerful as it wanted to be in this generation. Part of this was due to Psychic-type, which was the dominant type in Gen I. Outside of that, however, Fighting-types did not have powerful moves, with strongest move being 85 BP. This meant most Fighting-types had to rely on coverage moves.
Second generation of Fighting-type was a bit better, though not by much. The strongest new Fighting-type was Heracross, who was relevant due to its Bug-typing more than its Fighting-type. The other Fighting-types, Tyrogue and Hitmontop, just expanded on Hitmonchan and Hitmonlee. Nonetheless, this generation provided more moves like Cross Chop, brought in Karate Chop as a Fighting-type move, brought in moves like Counter, Mach Punch and Reversal. This generation also provided the first true Gym Leader for Fighting-type, Chuck, and brought back Bruno.
Third generation was significantly better for Fighting-type. First Fighting-type starter was introduced. Three new fully Fighting-type species were introduced, though two of which were rarer in their first regions than in later generations. Nonetheless, Fighting-type enjoyed a larger amount of support with moves like Bulk Up, Focus Punch(which became the core of SubPunch strategy), and Brick Break, which remains a common coverage move. Nonetheless, Fighting-type still had a long route to go.
Fourth generation with Special-Physical split introduced a massive new amount of moves like Focus Blast, Drain Punch, Close Combat etc. which changed Fighting-type forever. New Fighting-types introduced in this generation were offensively capable on both fronts(besides Gallade), though this generation remains the only generation where Special Fighting-types got spotlight. Introduction of Iron Fist and update on Jump Kicks were not too significant for this generation.
Fourth generation also made Elemental Punches a vital part of Fighting-type, as they were now physical, brought in Poison Jab as a common coverage move for Fighting-types, and made Superpower a common move obtained through Tutors, rather than a move that was primarily exclusive to Legendaries.
Fifth generation was partially the revival of the type, and partially its downfall. In the first phase, Fighting-type enjoyed new updates to existing moves like Drain Punch, Jump Kicks, as well as the new Throw moves. However, because Flying-types made a comeback in the second half of the generations, Fighting-types were hampered back, never to come back.
Sixth generation put the final coffin on the nail for the type with the introduction of Fairy-type. Fairy-type not only resisted Fighting-type, but was also super-effective against it, which meant that other types Fairy hit super-effectively against now were quad weak to the type. Scrafty, a popular bulky offensive Pokémon from the first half of Gen 5 was now completely useless, and its colleague Pangoro, which was introduced in this generation, was dead from the start. While some Fighting-type Megas enjoyed popularity, largely due to Pokkén, it wasn't anything signficant. The only common move introduced in this generation was Power-Up Punch and that was used exclusively by Mega Kangaskhan.
Seventh generation was a desert for Fighting-types. While the type finally got a pseudo-legendary to represent it, that pseudo-legendary was horribly weak. Other common Fighting-types like Passimian and Crabominable were also weak and hard to obtain, which made the type rather useless. Removal of moves like Rock Smash, P-Up Punch, and Dig also hampered the type a lot.Thankfully the legendaries that belonged to this type were very good, though two of them were far too good for their own sake.
The Overview of Fighting-types:
Fighting-type was seemingly conceived as a counterpart to Psychic-type, and that idea has only intensified in the recent years, especially after Dark-type was associated as an opposite of Fairy-type. This puts Fighting-type on the might side of the might vs. mind axis. Because of this, most Fighting-types are exclusively physically oriented, and there hasn't been any recent push to re-associate the type with Special since Gen IV.
In addition, the type, despite being treated as a primary-type from time to time, is really more of a descriptive type, and thus relies on being coverage to other types. Because of this, it is also one of the few types without a specific "domain", that is, a specific type of region where people would be expected to find Fighting-types.
Fighting-type also lacks Abilities that are directly associated with it besides Scrappy, though there are Abilities strongly associated with the type, they suffer from small distribution.