I have returned from playing a bunch of games on cartridge, and I'll post what I think after these games. It's mostly pokes already ranked and how they should be changed in ranking.
C ----> B-/B Rank: C for Serperior is a little low imo. Destroys any bulky water that comes in its path with Leaf Storm, and has the potential to clean teams once it receives a boost. Serperior can take advantage on bulky pokes in which it can take a hit from, which includes P2 and Cresselia. If you get a Sub up while they use a status move on you, you're golden. Unbelievable how many times I got a win off of setting up on Cresselia and P2, especially P2. Interesting fact: (It outspeeds high speed Mega Salamence High speed meaning adamant, etc.), so it can serve as a check to it if Serp has been boosted already or M-Mence has taken a bit of prior damage by using Dragon Pulse. However, the reason why Serp was considered C rank before was probably its fraility and lack of coverage. Leaf Storm/Dragon Pulse/Hidden Power Fire, Ground, Rock/Filler is all it has for moves if it's offensive, and those moves still lack the ability to hit some pokes neutrally, making it walled by pokes like Heatran if lacking HP Ground, Ferrothorn if lacking HP Fire, or MegaZard Y if lacking HP Rock. Serp can't take much hits at all either, so it relies on its speed to take out its opponents, and if it's outsped by a pokemon with at least a bit of offensive presence, bye Serperior. Still an underrated poke tbh.
B+ -----> A- Rank: This ranking upgrade may be a little odd, but I personally think that one of the top 12 pokemon used in Battle Spot Singles deserves to be somewhere in A rank. I've used this pokemon myself, and it is simply amazing. It has the bulk to take hits of Mega Salamence and retaliate with an Ice Beam to OHKO Mega Salamence after Double-Edge damage, which a majority of Mega Salamences run now. Scald can ruin pokes like M-Kanga if they happen to switch in at a bad time, or just try to set up on you. Speaking of which, it is a great user of Roar with its amazing bulk, not to mention that it can be an annoying move with Stealth Rocks up. Mirror Coat is amazing on it as well with the ability to take hits, OHKOing most special pokes that try to dent it. CroCune is great for bulky pokes that think they can win using status. Overall, it's a great bulky poke in general, arguably the best bulky water type in the metagame atm.
A ----> A+ Rank: Gengar is kinda scary to face. You don't really know if it's running a sash, LO to hurt pokes, spreading status around in its Mega Form, or even perish trapping Mega Gengar, thankfully that's getting less common (probably more common in high ladder tho). Gengar's unpredictability is the main factor that I think it should go up a ranking. That, and also HYPNOSIS. Hypnosis Gengar is becoming more of a thing now in the metagame, a majority of them holding Wide Lens (I saw about five yesterday in twenty games), and if that Hypnosis hits, and if you don't have something that resists Hex + Hypnosis well, your opponent will have the lead against you. Destiny Bond mindgames are luck-based and really annoying to get through, which can also create some serious problems in a match. Its typing is simply excellent as well, and it is basically something you can slap on a team and it will function well for the most part (that's what I've did.) This upgrade I may be a little iffy on, since Gengar is pretty frail and can be taken out with a faster pokemon with a somewhat strong move. BTW, the ranking should go up to its Mega Form, and possibly its regular form.
That's all I got for now. Will probably update on a few more pokes later on.