I don't think there is any need to ban Landorus-I at all. By getting banned to ubers, it loses the ability to hold a mega stone. Besides, if you are talking about whether it should still be able to hold a Mega stone I think that would be fine too--the power creep is real in this meta, and I don't think it would be too OP. Its best stones would probably be Absolite, Cameruptite (loses speed tho), and Ampharosite (loses speed again, but wallbreaks all the Aggronite mons), and I feel like with its abysmal typing (always 4x weak to Ice) and the speed and power creep in this meta is enough to leave it unbanned from ubers. I'm sure people will disagree though, and tbh, either way is fine, but I personally believe it is alright to let it hold stones in this meta.
Sorry, I should have specified, I meant lando-T is what we are currently suspecting. Also, its typing really is not all that bad, and the stones it does use right now are what make it both S rank and a suspect. LoPunnite gives it a usable STAB, better speed, and base 205 attack. Any of the -ate giving stones can increase its attack to 155-185, giving lando either a more reliable STAB or powerful coverage. It also gets a pre mega intimidate. If lando gets off a rock polish, and your team doesnt have any resists to its STABs you are pretty much done for. Offense struggles heavily against it when it uses an ate stone, and the loppunite set has almost completely different checks.