Metagross-Mega A -> A+
This thing is an absolute monster, and probably my favorite mon to use on the ladder. It's biggest selling point is it's ridiculously high stats across the board, with 145 Attack boosted by Tough Claws, 80/150/110 bulk and a very respectable 110 speed. With the exception of Zard, most of the top tier mons fail to check Metagross, as it can run Magnet Rise for ground types and Hammer Arm for Porygon-Z. Alongside it's powerful STAB in Meteor Mash, it has options such as Ice Punch, TPunch, EQ, Zen Headbutt and Hammer Arm. Meta is also a great abuser of substitute as it allows it to block Z-Moves and ruin Magearna. Although Metagross is often a victim of 4MSS it's unpredictability and sheer power should prove it worthy in the upper echelon of 1v1 mons.
Primarina B+ -> A-
Primarina is one of the tiers premier bulky offense mons. The Water/Fairy typing is a blessing, as it allows them to reliably counter ZardX and M-Gyara, arguably the two most powerful mons in the metagame. Primarina excels as a Torrent mon due to it's bulk, meaning that when paired with substitute it is easy to get into range. A Torrent boosted Oceanic Operetta will KO most mons that don't resist it even without SpA investment. Primarina is one of the tier's most formidable water types and thus deserves rise in ranking.
Tapu Fini B+ -> A-
This one is like it's other Water/Fairy fren but it has a few different tricks up it's shell. Instead of a strong water z-move, it instead usually uses Guardian of Alola, meaning that with Brine it's going to 2HKO almost any mon without recovery, while also having the option of a Waterium-Z set although it is usually outclassed Prima. Similar to Primarina, it too has the great privilege of defeating ZardX and MGyara and also threatens the other two S-rank mons. Fini is an excellent mon similar to Primarina and should get a rise along with it.
Jumpluff A- -> B
Jumpluff has faced stiff competition from other leech seed users such as Serperior and Whimsicott in the last few months. Unlike them, Jumpluff relies too much on Sleep Powder and is extremely susceptible to all taunt users. It isn't completely outclassed as a seeder however with it's ability to defeat mons with sleep that would otherwise OHKO it and likewise should be ranked similarly to the aforementioned Serperior and Whimsicott.
Serperior B- -> B
Serperior has seen a huge rise in usage for the right reasons. Similarly to other seeders, it's very fast and can win many matchups should it live turn 1 and set up Leech Seed. It makes up for it's lack of sleep moves with it's powerful Contrary + Leaf Storm, which allows it to 2HKO most mons which don't resist it.
Haxorus B- -> B
Although it struggles versus bulkier threats, Haxorus is a beast as it can defeat many of the tiers most common threats. It's most popularly run with scarf, becoming one of the meta's fastest mons in a tier where scarf usage is uncommon. This allows it to usually OHKO Dnite, ZardX, Lele and PoryZ, along with most other frail offensive mons. Alternatively, it can run band for ludicrous damage or Poisonium to take out PrimaFini. Overall a solid KyuB-esque mon that deserves a raise in it's ability to outspeed and KO many of the meta's fast offensive threats.
Tyranitar (Base) UR -> B+
This mon functions similarly to it's mega counterpart, however it can often be seen as the superior form through it's Rockium Z sets. Even without a Rock Tomb or Dragon Dance, a Rockium-Z Stone Edge will obliterate any mon that fails to resist it. It's ability to nuke any mon that it survives against should grant it a ranking alongside it's mega form.
Gyarados (Base) UR -> S
By no means does regular Gyarados' viability compare to it's mega's. Nonetheless, it does holds the niche of being able to defeat bulky grass types in it's Flyinium-Z set that would otherwise cripple the mega.
Eelektross UT -> UR
I'm usually up for interesting mons to be tested but this mon is straight up terrible. It sits at an awful 50 base speed, which means even with timid and scarf you're getting outsped by base 100 mons. It's got an awkward attack spread in 115/105 that makes it look semi-strong but not strong enough, meaning that even if you survive T1 you'll rarely pick up a KO unless you can use a STAB super-effective electric attack. It's got some decent coverage moves like flamethrower, superpower and iron tail but everything that it could potentially kill will outspeed it and kill this poor eel instead.
Togekiss A- -> B-
Togekiss is not good. It's bizarrely ranked higher than Jirachi who is arguably a stronger version than it, albeit without fast recovery. Togekiss isn't very strong or fast unless it's given scarf. Even with scarf when it fails to get the flinch it's under huge pressure from any setup mon or physical z-move, while Z-Thunder Wave loses to any fast sub user or hyper offense mon. It's ranking should reflect it's hax-reliance and it's low ladder usage.
Gengar-Mega C+ -> B-
A mon hindered by Hypnosis' terrible accuracy, Gengar-Mega is infamous for making uncertain matchups versus almost every mon. Despite this accuracy, the power to defeat so many mons, although inconsistently, cannot be understated and should result in a rank up for Gengar-Mega.
Zeraora B+ -> A-
Zeraora saw insane usage in the recent PL and it's no wonder why. It has a blistering 143 base speed, the fastest of any popular mon outside of scarf users. Zeraora has many viable sets that it can run such as Electrium-Z, Dragonium-Z and Life Orb. Along with this there are many moves it can run, from setup moves such as Bulk Up and Charge while also having offensive coverage in Outrage and Close Combat. Zeraora can be built to defeat all of the S rank mons and has made itself a staple among the premier mons of the tier.
Magneton B+ -> C+
Not sure why Magneton is ranked this high honestly. It is said to be run over it's evolution for outspeeding M-Gyarados, but this is bizarre as EQ usage on Gyara is about 50% regardless and the speed boost isn't giving you any other important wins. The bulk and power trade for 10 more speed just doesn't justify running it over Magnezone.