Okay so Relius vs Lambda... This is going off of what I have seen from pro matches and from my own experiences. In my honest opinion I do think I have a good grasp of the match up.
The big thing Relius has that most other characters don't have is murdering pressure. As we all should know, Lambda does NOT have many good options, if any at all to get out of pressure. She has her barrier block, her CA, calamity sword, and 236A (but not really lol). I can count all of her options on one hand, so going by this statement obviously it won't be hard to either eliminate 1 or 2 of the possible 4 options, or predict what she will do and react accordingly. Couple that, with Relius' godlike pressure, and its a nightmare for Lambda to escape, it just won't happen. Keep in mind that everything I have said is doable mid screen, don't even get me started on what its like in the corner against him.
Now, this is all assuming he gets in. What about taking 1 step backwards and trying to approach Lambda? Well you see that is not as hard as it may seem! While Ignis might not be as crippling as Ada is, she is still a big factor, and to be quite honest, Ignis is the only offensive threat that Lambda has to worry about. You can't attack Ignis, there is no point. She runs through all of Lambda's projectile based attacks, and she can go the entire screen. She does not require heavy positioning like Ada does. Not only that if she catches you with basically any one of her multiple attacks, its a free approach for Relius.
All in all Ignis is a beast and Lambda cannot just derp around, she WILL get crushed if she doesn't play it careful.
Last point about Relius. I will copy and paste this from dustloop since it basically sums this attack up quite nicely.
The biggest annoying move Relius has on him is a dodge-in-place move (will get name later). This move's startup is instantaneous, giving him seemingly full-body invincibility whenever he feels like it. Lambda has considerably more recovery time on whiffed attacks (especially D moves) than other characters. One whiffed move from Lambda can mean eating a full combo.
If Relius gets too spam happy, be sure to punish him on its recovery. I'm not sure if CH will be easy or possible to get on him, but take what you can get.
With this dodge move, Relius can use Ignis' attack-from-behind move to score a CH on Lambda, scoring a full combo. Watch out for this.
The dodge can feint out Counter Assaults. It's already hard enough knowing when to CA against A Character and His X, dodging in place between his attacks makes that window of opportunity even smaller to get him off you. You have to be really paying attention.
On wake up, Relius can dodge our 236D and even all hits of it if positioned normally... Positioning 236D a little further away from Relius probably works better against him since he will dodge the first few hits and recover on top of the last hits of the attack.
Also, if you're pressing him, 236X may get dodged by him completely. I don't recall any of the 236X series going past Relius (since A and B track his X position). However, 236C positioned correctly may hit him during recovery... or whiff miserably. Feel it out.
Obviously, this move will stop a lot of autopiloting pressure from us. Just remember, he has to take a guess when to use the dodge, make sure he guesses wrong or doubt the viability of it.
Now onto Lambda strengths in this match up. While Ignis can be a *****, she does have a gauge. Relius cannot just throw out Ignis all willy nilly, he has to be smart about it and if Lambda doesn't fall for any of those stupid little tactics he throws out, she won't have any problem against him full screen. I don't believe you can punish him for doing anything with Ignis, but at the same time taking a chuck out of the Ignis bar is more than enough of a win for me. Eventually he has to approach Lambda, and it won't be fun.
BUT he still does have the spin! Using spike chaser or the wheel against Relius is suicide. He can just spin out of Lambda's attacks and really dictate how the match will be played with one attack. BUT it is hard to land 100% of the time AND not only that Lambda can just bait it out and destroy him for spamming it. Its like I said earlier how Relius can limit Lambda's options and react accordingly. Lambda does the same thing while zoning vs Relius. While Relius does have very good options to get in, they are not spam able and he doesn't have many of them. Lambda can quickly eliminate some of what he can do and then punish him.
Lastly Lambda is a zoning character, and Relius is a rush down. Its just in their characters nature for Relius to have a hard time getting in, its the way it is. Relius has no super godlike options like D nails, or Hazama chains to approach. IMHO I think that Relius has one of the hardest times getting in, but one of the most rewarding if he does.
Conclusion
Don't **** with Relius. 50-50
