Karma/Ezreal: A pro play staple with insane poke damage, arguably the safest laning in the game and which allows you to go for absolute lane dominance.
Lulu/Kog'Maw: Kog loves steroids and staying alive, and Lulu can give him plenty of both. This lane is an absolute scaling nightmare, and Lulu makes it frustratingly hard to actually kill Kog early.
Twitch/Yuumi: What's better than one invisible champion? Two of them. This lane abuses Twitch's all-in power and makes his early damage a lot scarier, while scaling incredibly well.
Rell/Tristana: At level 2, you dive, and they die. Tristana can setup a really strong E by jumping on the opposite side of an enemy, and you have a great mix of early kill threat and scaling.
Braum/Ashe: Ashe slows you with W. Braum slows you with Q. Ashe keeps you slowed with autos. Braum's passive procs and now you're dead.
Nami/Jhin: Insane early trading power, with Nami's sustain rounding out Jhin's poke. Their ults combo well, and Nami's E - Jhin's W - Nami Q combo is both easy and lethal to pull off.
Tahm Kench/Senna: Especially if Senna is fasting, they nicely round out each other's weaknesses. Senna brings sustain, and Tahm brings reliable CC that chains with Senna's W, while her W chains his. One of the best 'run them down' lanes, with Tahm's R also helping to make up for Senna's vulnerability as an immobile carry.
Rakan/Xayah: Doesn't need much explanation, they were literally made for each other. Xayah loves hard CC that sets up her E, and Rakan has a ton of it.
Leona/Miss Fortune: Wombo combos galore after level 6, and laning dominance before then. Miss Fortune's early damage works well with Leona's sheer aggression.
Braum/Kalista: An incredibly aggro lane, where one Braum Q can quickly lead to a kill if Kalista is allowed to freely auto. Both of you have insane peeling after level 6 and a massive double knockup wombo combo.
Caitlyn/Morgana: A lane that sometimes pops up in pro play, their strong CC massively complements each other. Stepping on a Caitlyn trap is a death sentence, and Morgana's E makes it extremely difficult to punish Caitlyn if you can manage to close the gap.
Rell/Samira: Rell gives Samira all the hard CC she needs to engage, and the AOE damage is insane in teamfights. The knockup sets up Samira's passive, and once this lane gets ahead, you become almost impossible to shut down.
Thresh/Aphelios: A pro play favourite, Thresh makes up for all Aphelios' weaknesses - a weak early game, a lack of mobility, a need for a strong frontline who can start fights and a vulnerability to getting jumped on. The scaling on this lane is almost unmatched unless there's a Kog/Lulu on the enemy team.
Nautilus/Draven: If you fight them at level 1, you die. Nautilus brings all the point and click CC Draven needs to get the snowball rolling, and his ult makes it relatively easy for Draven to cash in all his stacks at level 6.
Taliyah/Pantheon: Regardless of which one is farming, there's nothing you can do to stop Taliyah landing her W-E with Pantheon around. This lane can easily snowball out of control.
Nami/Yasuo: Nami makes up for all of Yas' weaknesses in botlane. Her early trading compensates his lack of range, her W heal compensates Yas taking unecessary trades because he can E everywhere, and her selection of knockups makes his all-in extremely strong.