There's no reason Raticate has to be level 25-- it could easily be higher. :| My teams are usually close to 30 when I get to Celadon, and Raticate is in the same experience group as Hitmonlee. As far as I can tell, when STAB is calculated in, Raticate should be stronger (admittedly, I can't seem to find any online tools for calculating RB stats/damage... >__> Which does make it a bit hard to look up the facts myself...)
Regardless, it's a small point in the overall argument and problems with Hitmonlee.
You haven't addressed the point that Pokemon like Golem and Sandslash are held down to mid for their inability to get through the latter half of the game efficiently-- not in comparison to Water/Ice/Psychic/Electric-types. Golem and Sandslash even have type advantages against many key opponents, but they're just not as efficient as Vaporeon/Jolteon/Mr. Mime/Seel. Raticate really slows down in the later half of the game, and is inefficient for the same reasons-- and hitmonlee is no better than it. The mid-tier Ground-types are also better overall for more useful STABs, better survivability (mix of defenses and speed), and better match-ups type wise.
Why would I use Hitmonlee to beat Rock-types when it fails to OHKO them, takes huge damage in return, and are Pokes that could easily be taken out by just about any special attacker? How is that efficient? Just like its more efficient to use Vaporeon than Golem to beat an Onyx or Rhydon, it's even less efficient to use a Hitmonlee.
I have to be amused at your dedication to "equal experience distribution" because let's face it-- not all Pokemon are as easy to level up. Not all Pokemon snag wins and keep on going as easily, and Hitmonlee is one of those pokes that takes patience to get wins. Hitmonlee DOES get outsped, it DOES fail to OHKO a lot of foes, so it keeps having to take hits on its pathetic defenses. It takes huge damage, and can't beat more than a handful of enemy trainers before needing a visit to Pokemon center. It gets knocked out in battle alarmingly easily, even aginst foes that should be easy to beat. There is no way I could acknowledge this as high material.
Alright, let's address it. All of it.
Let's start with Hitmonlee's stats. While he has the bulk of a wet paper bag, His attack is the 8th highest in the game, and is only 14 base points off Dragonite's. Remember, you get this right after Surge, so no pokemon aside from Gyarados or Golem will have a comparable attack stat at this point. It's Speed is base 87, which is fairly quick for RBY. At this point you are still facing NFEs, who struggle to keep up. This is especially true over time as you gain stat exp, and will begin to outpace those at a higher base, like Jynx and Ninetails. Sure, you won't get near the likes of Alakazam without overlevelling, but you fight those very rarely.
Lets compare with the Ground types. Although the ground types have a higher special, this only means increased defense from Fire type moves and Electric moves, the latter which is almost non-existent after Surge. This means that Grass, Ice and Water moves, all which are abundant, will KO them regardless. Hitmonlee at least has a chance to survive them. And they are all slower, barring Diglett, so they will all be taking those attacks before they can KO. Being better all-round does not exactly help their cases - we can clearly see that High Speed and a High Attack/Special is all you need to be good in the game, and most of the Ground types have neither. Diglett is a prime example, with pitiful defenses, yet being Top-Tier with a decent attack and a high speed.
Let's compare Raticate. Raticate does more base damage with it's Normal-type attacks than Hitmonlee does with Normal-type attacks, but that is comparing apples to suspension bridges. Hitmonlee's STAB WAY overpowers Raticate's, due to better stats. If you really wanted to compare, compare Raticate's Dig to Hitmonlee's Body Slam, which also comes up worse, since they are both coverage moves and neither gets STAB. In fact, since Normal-types can't hit anything for Super-effective damage with their STABs, they are significantly weaker, giving Hitmonlee more utility.
Also, Hitmonlee at the same level always KO's Golem. Always. And Golem is never seen, rather you see Graveller and Onix instead. I've calculated it, and even at min damage assuming no Stat Exp, Hitmonlee always KO's Golem. In addition, a Wing Attack from Golbat never OHKOs Hitmonlee, assuming same level and no stat exp. That's to put it in perspective, meaning he can survive hits and KO pokemon which are rather defensive, so he is not exactly being KO'd back.
In fact, I have been doing plenty of calculations. Hitmonlee, despite having virtually no bulk whatsoever, is able to survive SE attacks from the likes of Golbat and Pidgeot, meaning he can set up a Meditate and KO the rest of the party the next few turns. Alternatively, he can just 2HKO.
After a meditate, which is often possible to set up, Hitmonlee can KO pretty much anything he outspeeds. There are just a couple of pokemon in the game he really can't KO without being a slightly higher level, like Gyarados or Ninetails. However, that's only if they use their best attacks as many pokemon in this game carry Junk moves.
How can't he get through the late game? He motors through Cycling road despite all the Poison-type pokemon, and the other route has plenty of Water and Normal pokemon that he can cut his teeth on as well. By the time he is down to Koga, he is very well levelled. In addition, he takes out this team with ease as you can set up on his Koffings. While Koga is harder in Yellow, he can at least take out the 3 Venonats guarranteed, and should do around 70% damage with Body Slam to Venomoth (2HKOing it if it uses a Junk move). While he cannot take the ghosts in pokemon tower, he can certainly take on the wild Cubone/Marowak as well as the Rockets on the top level.
He then goes along the route to Cinnabar, KOing all the Water-type pokemon on the way with ease. This is because most of those will either be NFE or will have pitiful defence. After that, he should be at a sufficient level to take on Blaine in Red or Blue (or Yellow if you can set-up on Ninetails without him KOing you with Flamethrower). Following that, you head to Giovanni's gym (use someone else to handle Sabrina), take out his grunts and then face him. You set up on his Rhyhorn, who only has junk moves, and then you sweep with +6 Hi Jump Kick or +6 Body Slam. From there on you take on the E4, sweeping Lorelei (KO Dewgong and then set up on Cloyster for the rest of the team) and Bruno (He can practically wall Onix). He falters to Agatha, sure, but we all knew that. If he comes in after Gyarados, he can sweep Lance by taking advantage of Agility and setting up to +6. He can then go onto set up on Rival's Pidgeot, only to +1, depending on what it does, and then do some damage, losing out only to Alakazam, Charizard and a select few others.
That's a pretty good late-game stretch to me. This pretty much means he only could ask for Dugtrio, Alakazam or Zapdos as a partner, and he's pretty much set for the end game.
And compared to the other types, that's actually better than most. Ground types hate Lorelei and Sabrina, as well as the stretch of water trainers before Cinnabar. Grass-types despise Agatha, Blaine and the trainers along Cycling road. Water types have trouble with Lorelei as well, although they do finish off well. So not everyone has great match-ups where Hitmonlee does.
And it does not matter if you think it is outclassed, that is not the issue. If I wanted to use Hitmonlee no matter what, I should see it weighed on its merits rather than a comparison.
And no, before you complain about setting up, he only should be doing so on the important battles. The scrubs he fights on the way don't weaken him because he OHKO's them along the way. Yes, Raticate and others can set up as well, but that does not detract from Hitmonlee being able to do it too.
He is really efficient as well, as you only use 1 TM on him (and that can even be Strength if you are a bit of a miser), and maybe a couple of Super potions along the way. Fairly inexpensive as far as pokemon go. He comes from a decent EXP area, at a decent level and within decent range of pokemon he can grind on. Hell, you can take him down to Celadon dept store and clear that out with him with just any set of normal and fighting moves.
I'm not blind to Hitmonlee's flaws. He would really love Rock Slide for coverage, that's to be sure. Or Earthquake to hit the Ghost-types. And I'm not appealing for Top, he doesn't break the game. But still, he adds great value and can be a great compliment to pokemon like Charizard and Zapdos. High-tier is where he should be, with the other pokemon of his ilk. He doesn't really falter, there are just some pokemon he cannot get around.
Edit: And now I'm off to bed. If you have a rebuttal, I'll address it sometime tomorrow, probably around 10pm my time.