Luka Couffaine is only in like, 19 episodes, so here's the list from the top of my head:
Episodes where Luka and Adrien Interact in Some Capacity (some ARE a stretch but I've had Lukadrien brainrot for literal years):
Season Two:
Episode 16: Captain Hardrock (Luka introduction, iconic 'Welcome to the Band')
Episode 17: Frozer (sure it's a bi-square ep but watching through a lukadrien/marigami lens is so fun)
Season Three:
Episode 7: Silencer (Silencer calls Chat Noir 'kitty' and no one ever talks about that)
Episode 11: Desperada (the whole episode. no explanation needed)
Episode 20: Party Crasher (Luka comes to party uwu, Vipernoir moment)
Season Four:
Episode 1: Truth (anytime he's akumatized and interacts with Chat Noir is so fun to me. 'do u love me? beat me up pls' also both times they really emphasize hand-to-hand combat)
Episode 12: Crocoduel (no Lukadrien bc 'GOTTA KEEP ADRIEN AWAY' but lukanoir is a fave of mine)
Episode 13: Optigami (a stretch, absolutely, but the idea of Luka coming to a model thing for Adrien is so funny and cute to consider)
Episode 18: Wishmaker (Iconic, the whole episode. 'you don't want to be a model Adrien, i hear your melody' etc; kicking and screaming)
Episode 19: Ephemeral (pls watch this with a Lukadrien lens, Chat Noir's shocked face at Viperion de-transforming makes me cackle every time)
Season Five:
Episode 6: Determination ("He loves everyone and everyone loves him back, he's surrounded by love and has a hard time understanding it all")
Episode 12: Perfection (the song one. You know how they look at each other at band practice)
Episode 13: Migration (*through gritted teeth* "this way, CHAT NOIR can come help us" *shoves Adrien in the closet*, oh and of course "'what would I do without you")
The episodes Luka appears in that he doesn't really interact with Adrien/Chat but just merely appears:
Season Three:
Reflekdoll (complimenting Juleka)
Heart Hunter/Miracle Queen: (cute biking sequence, Marinette sobbing into his arms)
Season Four:
Lies (being the inverse to Truth ofc)
Sole Crusher (party on the Liberty)
Penalteam (Viperion is trapped in the bubble for the wHOLE GAME) Risk (barely there as Viperion)
Strikeback (Luka gets a :o moment)
Season Five:
Re-creation (comes back fINALLY)
tldr w/out my commentary:
Season Two:
**Episode 16: Captain Hardrock
Episode 17: Frozer
Season Three:
**Episode 7: Silencer
**Episode 11: Desperada
Episode 20: Party Crasher
Season Four:
Episode 1: Truth
Episode 12: Crocoduel
Episode 13: Optigami
**Episode 18: Wishmaker
Episode 19: Ephemeral
Season Five:
Episode 6: Determination
Episode 12: Perfection
**Episode 13: Migration
**personally view these as the Most Lukadrien:tm: episodes
