Okay, so I think that BlastFury did a good job at listing the Pros and Cons, etc. But he didn’t say which one is best, that is where I come in. So, I think we should lost the Pros and Cons first, which would be:
Hitmonlee
Pros:
- Amazing Attack and passable speed.
- Great STAB Fighting moves available.
Cons:
- Incredibly weak defenses.
- No Coverage Moves
Hitmonchan
Pros:
- Good Attack and Defense, and moderate speed.
(Unlike BlastFury, I do not think he has good coverage. What use are special moves if your Special Stat is 35?)
Cons:
- Terrible Special
- Best Fighing Type Move being Submission, a bad move when you can have High Jump Kick on Hitmonlee.
In the end, I would go with Hitmonlee. Even though it isn’t very bulky, I think it is the better option here. It has a better fighting move then Hitmonchan, and even if you don’t want to use High Jump Kick because it is risky, the speed and greater attack is more valuable then Ok Defense on Hitmonchan. But, I know this is Blue, but if you ever do a Red Nuzlocké or something, don’t use the Hitmons as a fighting type, use Primape, because it has access to Dig, Rock Slide, Thunder/Thunderbolt with passable Special, and good Speed and Attack. However, as this is Blue, Hitmonlee is your best fighting type here.
Hope I helped!