Adon
Birdie
This match-up is one of the most Scuttle-Cancel heavy match-ups Lee has. If you know how they work it's not a great match-up, if you don't know it's brutal. Birdie has a light kick loop on Lee that makes this match-up scary for Lee. The best course of action is to use medium kick to prevent Birdie from getting in. Jab beats Birdie jump attack pretty consistently if timed right. Medium Kick goes under Birdie Headbutt but Birdie Headbutt goes over Medium Kick so which ever one comes out later usually wins. You mostly have to focus on keeping Birdie at bay while trying to get enough of a health lead to win by attrition. If you land a heavy punch close to Birdie you can loop a second one but it drops after that unless he is in corner.
However if you have mastered scuttle-canceling Birdie's loop is significantly less dangerous. You can buffer jab after the scuttle cancel and then buffer back jump to escape or just scuttle cancel and buffer jump forward and jump through Birdie. If Birdie jabs he can beat jump forward but it won't cover back jump. The single most punishing escape when not in corner, however, is (scuttle cancel Birdie Light Kick -> buffer jab(11 frame window) -> buffer back walk(12 frame window) -> buffer medium kick(7 frame window) If Birdie buffers light kick (or tries it at all) he will get hit and you get away for free. Of course if Birdie doesn't buffer light kick he may punish you so be careful if fighting a mindful Birdie. In corner you have to buffer jump forward, however Birdie can jab loop you in corner so it might be ggs anyways.
Overall, just keep Birdie out the best you can, it's still a fairly Birdie favored match-up with scuttle-cancels, but without them it can feel almost impossible.
Eagle
You'll be pleased to learn that Lee is one of Eagle's worst matchups. Your damage is about even and you can shut him down if you play your cards right. Don't think it's a free matchup, however; Eagle's a strong, volatile character that can easily take the game if you let your guard down. Stay aware and keep him in check.
Your best course of action is to stay at least half-screen from Eagle. Depending on the other player's plan, they might try to go aggressive, or stay out of your HP range and turtle. HP is great in this matchup but should be used carefully. If you're throwing HP out predictably, the Eagle can punish you hard with moves like HP, that can potentially do up to 50% of your health. If used unpredictably, however, it's a great tool to condition Eagle and make them respect you more.
MK is fantastic against Eagle. He struggles to contest it well due to the crouching and long range, also giving you time to approach on hit. Use it.
Jump kick is strong to close a life deficit gap if necessary; it's also surprisingly clean when it comes to air to air provided it's done early enough. Eagle's going to be looking out for it, however. Make sure the Eagle's unaware before throwing it out or you'll eat a heavy anti air.
One important, but not necessarily easy, thing you'll have to maintain is remaining proper distance from Eagle. Lee's terrible up-close options make it so if you get cornered you likely won't get out. Jump back when needed, do not get too overzealous with jump attacks or HPs. If you're close after a jumpin, jump back or MK. If you manage to corner Eagle, play it safe and play at the tip of your MK range, but don't get too fixated on keeping the corner.
Watch out for Eagle's jump; it'll go over all your attacks and can screw you up if you aren't spacing yourself to deal with it. The most consistent option if he jumps from far away is to punish his landing with an MK. If he's closer and tries to jump, try to go under him with walking or HP to maintain spacing. MP and HK can situationally work as anti airs, but be aware of the ranges and timings where they'll work, because if the anti air backfires, it'll hurt. Scuttle-cancel is very dangerous in this match-up and generally should be avoided, especially into Eagle Spin as it essentially causes instant death.
Videos of the matchup:
https://www.youtube.com/watch?v=JsQ3LVb1wnQ
https://www.youtube.com/watch?v=LeF6v6QzAJc
Geki
Gen
The fight versus Gen is a surprisingly even one, albeit a bit Gen favored. Lee's HP is one of the best counters to Gen's scissor kick (MK/HK) in the game due to its range and damage. Learning to react to the opponent's scissor kick or being able to predict when they'll use it is incredibly powerful for a safe approach. Jumpkick is another great means of approaching him, but if done too predictably, he can block it and counter for big damage. Cool off on the jumpkicks if the opponent has a read on you.
The biggest struggle against Gen will likely be dealing with his own jumpkick. Lee doesn't have a particularly strong set of anti-airs, so you may struggle to find a consistent counter to jumpkick-heavy Gen play. The best answer is if you're expecting a jumpkick from Gen, do a jumpkick yourself. Lee jumps a fair bit higher than Gen, and over his jumpkick hitbox, so Lee can contest him in air-to-air quite well. There's no way to anti-air Gen on reaction, unfortunately, so this is your best bet.
The dynamic of the match can shift pretty heavily depending on what your opponent is doing, so be sure to keep an eye out for the tools they're using and decisions. For example, Lee can get away with being quite aggressive in this matchup, but not if the Gen is fishing for a block. If he's doing that, then it's best to wait him out with fake outs until he lets his guard down. Overall, Gen is a bit better in this one but it's very winnable for Lee regardless.
A video of the matchup can be found here: https://www.youtube.com/watch?v=ZG-x8UGw1Uk
Lee
Joe
Mike
This matchup is very much in Lee's favor, primarily due to MK blocking out Mike's approach most of the time. Use a lot of it! Honestly, for the most part, that's kind of it. Use a lot of MK to keep him away (but don't get too careless). You can try getting a surprise attack with HP, but it's very risky and probably isn't worth it.
Retsu
Retsu is a amazing matchup for Lee. HP is a rock-solid counter to Retsu's infamous HK. You may have trouble with Retsu's jumpkick more than anything else, but with block -> LP -> MK you can anti air it with solid reactions and punish. Tread carefully against more aggressive Retsu players. MK is a solid option up close, since it ducks/outpokes most of his moves. If you play reactively, you should be able to beat almost any Retsu that comes your way.
With Scuttle cancels you can buffer HP to punish Retsu Heavy Kick and start looping Retsu. You definitely don't need it in this match-up but it's some extra sauce to make a dominating match-up even more dominating.
Since Retsu can't Jump attack safely and can't Heavy Kick safely he ends up having no really way to stop Lee from steam rolling him. Basically wait for Retsu to throw out a punishable attack and then demolish him. If he doesn't an is just jabbing and medium punching just HP at range and start a loop on him. Very easy match-up once you understand the flow of it.
