Mega Camerupt to C/C-
One of the best possible STAB combinations, with the movepool and attacking stats to deal a lot of damage, good bulk with a nice defensive typing, and a somewhat useful ability pre-mega evolution, too. It's also great under Trick Room, a and beats lots of common Pokemon like Talonflame, Volcarona, Gengar(well, maybe), Blaziken, Serperior, Thundurus, and Aegislash. Obviously it has problems against lots of Pokemon like Garchomp and Rotom-W, but even most of these will take a lot of damage if you manage to get an attack in thanks to Sheer Force and good moves, that's why I think a D is too low for this guy.
Milotic to C/C-
Milotic is pretty close to Vaporeon in viability, I think: same type, slightly better ability, worse bulk overall, and slightly less SpA. It also has reliable recovery(which Vaporeon only has when running Protect with Wish, killing two move slots,) as well as some interesting moves like Mirror Coat, Coil, Light Screen, and Magic Coat.
Armaldo to B-/C+
Armaldo is really good-I don't know why it isn't more popular. I use it with an Assault Vest(the extra SpD is a huge boon, and Armaldo doesn't really care for Status category moves thanks to its great offensive move pool), though I can think of a few other sets that would be reasonable to use. With an Assault Vest, you can reliably check Gengar, and break a possible sub with Rock Blast. Speaking of Rock Blast, it ruins things like Talonflame, Mega Charizard Y, Volcarona, Thundurus, Mega Salamence, and a few others. The other three moves I use are Earthquake(great for Heatran, non-sub Mega Gengar, so you don't need to risk a miss with Rock Blast, Bisharp, Aegislash without an item, or when it might use King's Shield, Mega Mawile, Blaziken, and some other stuff, Knock Off for its great utility and power, demolishing Eviolite users and things weak to Dark alike, and Aqua Jet, mainly for its priority.
Regice to C/C-
I'm sure some people remember me advocating for Regice to be ranked. It has really good coverage, ice STAB is great and takes care of the plethora of Dragons and other Pokemon weak to it, though you may need paralysis/Trick Room support so you can OHKO them before they OHKO you, or Reflect so you can survive their attacks. Thunderbolt, or Charge Beam, can be very useful for Pokemon like gyarados, and completes the famous BoltBeam coverage. Focus Blast is useful for a lot of Pokemon like Kangaskhan, Tyranitar, Bisharp, and plenty of other Pokemon, though it's accuracy means you shouldn't always use it, even when it's the stronger move. Lastly, I like Ancientpower for the ubiquitous Talonflame, as well as its ability to deal with things like Mega Charizard Y. That probably sounds silly, but Mega Charizard Y's Fire Blast in the sun is a guaranteed 2HKO against 252/0 Assault Vest Regice after Stealth Rock-it's a 3HKO if you have Light Screen on your side, effectively allowing Regice to check the strongest special attacker in the game, even when it's using a super-effective STAB move boosted by the sun. That should give you an idea of how little damage AV Regice takes from Suicune's uninvested Scald, or its +6 Scald, for that matter. Even so, physical attackers are more common than special ones which is the only reason I'm only suggesting Regice be ranked somewhere around a C.