SV has several good fighting Pokemon, like Quaquaval, Hawlucha, Flamigo, and Lucario. Quaquaval is unobtainable if you choose another starter, and Lucario is better if you catch it at a high level after defeating Klawf, so I recommend using Hawlucha or Flamigo.
Both of them can be caught at level 22 and 17, respectively, before battling Klawf. They have high physical attack and speed stats without needing to evolve and can immediately learn low kick, which is an easy 2HKO on Klawf. You can use wing attack a few times to prevent anger shell from activating. After defeating Klawf, their physical attack stats, offensive typing (especially if you use a scrappy Flamigo), and STAB moves' base power lets them continue steamrolling boss battles for the rest of the game. Acrobatics, high jump kick, and close combat are both powerful and spammable despite technically having drawbacks. They also learn useful coverage moves, like dig and stone edge for Hawlucha and throat chop for Flamigo.
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