Can we please talk about legitimate things? Reshiram for A rank??? WTF? First off, it's outclassed by Primal-Don as a fire type. It's outclassed by the Lati twins (and probably others) as a dragon type. It doesn't really boast anything special like it used to. Primal-Ogre can use it as CM bait or just scare it out. As soon as it drops a draco, Mega-MegaMence; Rayquaza; Xerneas; [insert name of setup sweeper] has a free turn essentially. Reshiram is good for its surprise factor, but is fairly predictable and not hard to beat. It's the same reason Zekrom lost quite a bit of its glory when ORAS came about. Reshiram is at its very best a C rank, and that's being pretty generous.
Palkia... Are you serious? Honestly I'd say it should move down to C- Rank. It can't use a single water move against primal-Don, it will barely ever switch into Primal-Don, especially an offensive variant. Depending on the moveset, Palkia can be straight up walled by Primal-Ogre, a pokemon it's supposed to be able to check. Not to mention Palkia is outclassed by other dragon types which are virtually better in every way generally to say the least. By the way, remember how viability is also determined by general scenarios a specific mon will tend to create? Well if one mon is strong in its own right but carries a risk of being easy setup fodder for dangerous sweepers, then its validity drops... Palkia is C rank because Xerneas, CM Primal-Ogre, E-killer Arceus, Darkrai, various CM Arceus, and even Double Dance Primal-Don can use it to setup. So, there are at least 3 (common) very dangerous sweepers in that list which can use Palkia as fodder. Palkia also has virtually no way of getting past dedicated special walls in the tier, such as Lugia, some Support Arceus forms, and Blissey. Palkia just isn't very good right now. It might have a decent matchup against a few things, but a good player has a brain and can play the game too. Palkia just comes up short more often than not.
Mega Lopunny... Uhm... No. D/C- rank. It's quite speedy and hits ghost types but it lacks quite a bit of power in regards to the general bulkiness of everything in the Ubers tier ever. It hits Mega-Sableye. Good for it. It can beat Mence and Ray with Ice Punch. Good for it. I has HJK to hit... Dialga, E-killer Arceus, and whatever else it's super effective against AND it outspeeds AND OR it survives a priority hit from. Mega Lop doesn't have anywhere near enough bulk to hard switch into very many moves, meaning it can only seriously act as a revenge killer in most cases. Like Mega-Kanga, fake out acts as a double edged sword. Mega Lop will essentially get KOed if it misses out on getting a KO. So, yeah... Mega Lop has a nice niche with speed and coverage, but it lacks the proper bulk and raw strength to really pose huge danger to a majority of the tier. It's also Outclassed by E-killer Arceus' and Mega-Kanga, the latter of which has more bulk and gets 2 hits instead of 1 while having a fairly similar moveset.
Landorus-I should be D rank in my opinion. I barely even understand why it was moved into Ubers at all. Landorus-I in OU was great, but I honestly don't feel it should have been banned from OU. As much as I would rather talk about why Landorus-I should go back to OU, I know that this isn't the place. (I don't think it is anyway.) Landorus-I boasts incredible potential, but in Ubers... It will basically never meet that potential.
Here's a list of checks: Primal-Ogre, Yveltal, Bulky Mega Mence (without HP Ice), Arceus Norm, Darkrai, Mewtwo, Deoxys-A, Offensive Mega Diancie, Arceus-Water, Arceus-Ghost, Latios, Latias, Lugia, Mega-Gengar, Shaymin-Sky, Support Dialga, and Mega-Bro... This list also adds more things as Lando-I is worn down. There are also a few walls for it, such as Lugia and Primal-Ogre just to mention two of several. Lando-I is forced to run life orb (or choice specs I guess) if it is supposed to achieve the needed damage for KOs in the first place, which means that a number of scarf users beat it. Lando-I is so heavily outclassed by other ground types in the tier that there basically is no reason to use it on a team as opposed to something else. It has no real usable flying STAB move. It can virtually never act as a counter because of its frailty in Ubers. It has very little chance of ever setting up a CM effectively. It lacks priority and is curb-stomped by common priority users, such as Arceus and Yveltal. Honestly I'd say Lando-I has little to no viability in the tier to be completely honest. Not worthy of anything above D rank.
I'd like to also take a minute and say Deoxys-S up to A+ rank. The speed form is basically better than any other lead for hyper offense in my opinion. With a way to get around the 2 magic bouncers and the added ability of being able to taunt makes it exceptionally good at its job. It may not be the best hazard setter in the tier arguably, but it is really good at providing that support that several other mons just can't. It also outspeeds the whole tier and doesn't need to run hardly any speed to do that. I think Deoxys-S is really good right now as an alternative to Primal-Don if you want to run a team that's more geared towards HO. I think the main thing is the tier is between Balanced Offense and Hyper Offense with some variations and discourse generally speaking. Like, I've never actually seen stall the entire time I've played in Ubers ever since ORAS. Rapid Spin is virtually hard to make use of for quite a few teams because only a certain number of viable mons learn it. Defog support usually comes from Latios (I'll be honest, everyone uses Latios unless healing wish works much more for their team) or Support Arceus. With a meta that is filled with "If I set this up I might win right now on the spot," mentality, there are times where it isn't easy to use defog, especially when you see certain threats that can come in on a predicted move. That's right, I'm looking at you Mega-Mence. And Xerneas. And Arceus... and... well you get the idea. I don't think Deoxys-S offers enough support to seriously be taken past A+ rank, but right now, it does its job exceptionally well and has a way of benefitting HO teams with spikes and rocks without using 2 separate mons. I think that its support is why is should move up. It also tends to force players to quickly remove the hazards if at all possible because having just 1 layer of spikes and stealth rocks up will more often than not give a substantial advantage to the player who put them up. If E-killer arceus gets 1 SD off with that same scenario, I literally see nothing that stops it from straight up walking over the opponent besides D-bond Mega Gengar and Ghost Arceus. Sorry for the long post, I just felt like the forum was starting to get off track.