If there's no riolu please tell me that as well.
I am presuming that this is for an ingame team, so I would say that Hitmonlee is.
It has great attack and speed and a decent sp. def and is the easiest found, as it is obtained after beating the fighting dojo. I would have recommended Heracross, but it is found after beating the champion and Machamp is only available if you can trade.
Hmmm, I would say Heracross is the best in my opinion but you can only obtain it very far into the game. If you want a good fighting type faster I would head after Hitmonlee. No you can't get Riolu sorry
Machamp is the best non-legendary Fighting type Pokemon out there, but is it only obtainable through trade. Machoke is still a good choice, but you might prefer Hitmonlee since it is given to you for free by the Fighting Dojo and has very good speed and movepools.