This'll be fun, I got some ideas, but this will be probably long.
Kazuya
Vs. General
"Did we really have to fight?" (No loses)
"I hope that was enough for you." (1 round lost)
"You're pretty strong, but you should use that power for better things." (Low HP and 1 round lost)
Vs. Tatsuya
"Were...you holding back...?"
"I still get amazed that you can do so much at your age...!"
"I wasn't expecting any less, I'm lucky to even be on my feet...!"
Vs. Raidou
"Hey, no fair! You weren't fighting at you fullest!"
"Was my resolve equals to yours?"
"As expected from the legendary Kuzunoha, sigh I think I should go to the hospital..."
Vs. Delta
"Maybe you should train a bit more next time."
"Do you mind if I join you on your training next time?"
"Wow...! What do you and Yu do at the mountains to get this strong!?"
Vs. Gamma
"Ice Age is strong, but I feel like... you spam it a little. Stop that."
"That staff of yours... have you considered getting a lance or halberd?"
"You've definitely gotten stronger, one wrong move and I would be dead...!"
Vs. Kalib
"C'mon man, you OWN GYM, I know you can do better."
"You may not be a Wild Card or all that experienced, but you hit like a truck...!"
"When I first met you, I thought you were a mostly normal guy but... your resolve is anything but normal."
Vs. Ene/Clearing Eyes
"Again, why would you want to fight?" // "When you don't have another person to use as a shield, you really ARE weak."
"W-Why are all the girls I know related to electricity...?" // "Your trickery is really getting old, Serpent."
"Okay, I will admit I underestimated you, that thunder of yours nearly killed me!" // "...And stay gone."
Vs. Teddie
"No Kamui Miracle to save you this time."
"Don't rely so much on luck. Hone your own strength too."
"Hey- Stop trying to trap me with that move of yours! I'm not falling for it!"
Vs. Prima
"Next time, we should fight as a team rather than against each other."
"If only demons were more like you."
"...I kind of want to see your world now."
Vs. Yoshiko
"C'mon, where are you looking at, Yoshi? Focus."
"You're getting there! Hmm, maybe I should get you a COMP...?"
"Wow... I-I mean, uhm... What I mean to say is I... I'm proud you've gotten this far...!"
Vs. Shihiro
"We'll keep this up until you drop that attitude."
"Good but try to fight in sync with your demons."
"It's clear now, you can fight as a team. Next time, you'll be fighting my demons too."
Vs. Yuka
"Trust me, I've gotten used to getting shocked by now. I'll tell you later though, it's a long story."
"I can never lower my guard, not when you're being this serious. Hahaha, it's a bit scary!"
"You've always been stronger than I am, and I've always relied on you but... I hope you feel the same trust I feel for you, Yuka."
Vs. Lucifer
"I still remember what you tried to pull with Beelzebub years back, at least this time you tried to deal with me personally."
"I get your ideal. But as long as vulnerable people exist, I'll oppose you every time."
"It doesn't matter what you pull, your power alone doesn't cut it!"
Vs. Archangel Michael
"Your high and mighty attitude means nothing if you can barely fight."
"It's a mistake to look down on us humans. That is why you will always lose."
"Once you're back up there, go and tell Him to beat it!!"
Vs. Tyrant Asura
"The bigger they are, the harder they fall, right?"
"With that many arms I can barely tell what you're about to do, and even then, you're too predictable."
"You are strong, too powerful. But true strength is not just brute force, it also comes from the mind."
Man this was really long, I know too many ppl lmao