I'm pretty sure Lee wrote the analysis, so you can take it up with him :)
Soooo NixHex when's the next poke? I think we've exhausted Landorus-I :x
Not quite, there's still one route we haven't explored: flyers. Maybe there's a flying / levitating mon that is so cool it isn't ohkoed by EQ and can ohko back (nor is it 2hkoed by SE or HP Ice)
i'm checking them right now btw, it doesn't look good though
E: OK so so far i've found Rotom-C/W (Landorus does ~70% max, Scarf set retaliates with an OHKO)
Max Defense Weezing manages to /just/ avoid the KO from EQ after SR and Sand burn with WoW but that's all it can do (but really, that's enough)
Claydol is 3hkoed by HP ice after Rocks, so it can KO with Ice Beam
Uxie can tank like 400 hits from landorus if it uses dual screens, and eventually KO with Psychic. I'd say it works.
Cresellia can eat an EQ or 2 SEs with ease and KO with Ice Beam. Counter. Unfortunately, its main recovery is completely neutered in sand.
And those are the only counters that are even worth pondering of the levitate / fly list (none of the fliers worked.)
So, in pretty form:
Rotom-C @ Choice Scarf
Levitate
Timid / Modest
252 SpA / 4 SpD / 252 Spe
-Leaf Storm
-Thunderbolt
-HP Ice
-Trick / Volt Switch
Can come in on Landorus, worst case scenario takes about 80% from rocks, sand, and LO HP Ice, can KO back with its own HP Ice. Not a perfect counter, but it works.
Rotom-w @ Choice Scarf
Levitate
Timid/Modest
252 SpA / 252 Spe / 4 HP
-Hydro Pump
-Volt Switch
-HP Fire
-Thunderbolt/Trick
step 1: come in. step 2: don't get critted. step 3: don't miss. step 4: ??? step 5: PROFIT
Weezing @ Leftovers
Levitate
Bold
252 HP / 252 Def / 4 SpA
-WoW
-Pain Split
-Sludge bomb/Clear Smog
-Flamethrower/Thunderbolt
IF you come in on anything other than Gravity, you're golden, and all you have to worry about is your mental health (after all, you're using Weezing in OU...). If you come in on Gravity, then Landorus will proceed to EQ your ugly face into the very very red part of the health bar and you hope you hit with WoW, a noble sacrifice to save the rest of your team from sure extinction. But knowing your luck, you probably didn't.
Claydol @ Leftovers
Levitate
Bold
252 HP / 252 Def / 4 SpD
-Ice Beam
-Stealth Rock
-Rapid Spin
-Earth Power
Lando's most surefire counter, also spins! What a handy guy. HP ice is a 3hko no matter what, so you can even take your time and spin a little before you dispose of lando with a quick ice beam. Definitely landorus's best counter, surprised he has not been yet mentioned.
Uxie @ Light Clay / Leftovers
Bold
Levitate
252 HP / 252 Def / 4 SpD
-Reflect
-Light Screen
-Psychic
-Yawn/Memento
Come in on lando and set up a reflect. Then keep hammering away; eventually, you'll kill the lug. Also grants team support. Handy!
Cressellia @ Leftovers
Bold
Levitate
252 HP / 252 Def / 4 SpD
-Moonlight
-Psychic
-Ice Beam
-Thunder Wave/Toxic
If Dual Screening Pixies aren't your style, you can always opt for this space duck who got banned from the RU tier! (not to be confused with Porygon-Z, the OTHER space duck who got banned from the RU tier). simply come in, ice beam, and weep as you realize your recovery is worth absolutely nothing. but hey, there's a dead landorus over there so stop whining.
edit: cress was already mentioned, whoops
EDIT3: HOW DID EVERYONE FORGET ROTOM-W?