Well, useful Fighting types in Reborn are Hawlucha, Hitmonlee, Machamp, Mienshao, Scrafty and Toxicroak (an Lucario is decent), all of which are either later game or need something from later game to really shine. For example, Scrafty is only average if you don't get it Dragon Dance and an actually useful 4th move (ideally one of the punches from Hitmonchan), so you'd need to wait till Route 1. Same for Toxicroak, you can get it really early, but it needs either Bulk Up from Mienshao from Route 2 or Vacuum Wave from Hitmonchan from Route 1 to really stand out. Mienshao, Hawlucha and Hitmonlee can be used pretty much as soon as you get them. The easiest-to-use Fighting type would be Machamp, and you've already got that :/
If you wanna use any of those^^, sets would be, in order:
-Mold Breaker, Max Attack and Speed, Adamant; Acrobatics, SD, High Jump Kick, Dig/Rock Slide (via pre-E13). You could also use a Flying Gem and Unburden, or a Hone Claws set with Bounce.
-Unburden, Max Attack, 100 Speed, rest in HP, Adamant; High Jump Kick, Blaze Kick, Rock Slide (pre-E13), EQ/Bulk Up (pre-E13). Stack up and a ton of Fighting Gems. The reason for 100 Speed is so that, after Unburden, you outspeed base 110s.
-Skipping cause you're tired of it.
-Reckless, Max Attack and Speed, Jolly; HJK, Knock Off, Poison Jab(pre-E13), Acrobatics.
-Moxie, Max Attack and Speed, Jolly; HJK, Crunch, Dragon Dance, Ice Punch.
-Poison Jab, Max Defense/HP and Attack, Adamant; Drain Punch, Bulk Up, Poison Jab, Sucker Punch. Simple stuff. Poison Jab>Dry Skin cause it gives you a 30% chance to poison with Sucker and Drain Punch, and a 44% chance to Poison Jab.
And alternative would be Dry Skin, Max Speed and Sp.Atk, Modest; Vacuum Wave, Nasty Plot, Sludge Bomb/Wave, Dark Pulse.