So many pokemon so I'm going to try and bulk this out. Just like the mast multi-descrip, I'm only going to cover some key points.
First up for the 18th is the Bug we've probably all come to be deeply annoyed by, Beetelord. Despite Maud's Beetelord being obviously easily beaten, Beetelord is a monster. While its stats aren't ideal, it has a nice typing and goo movepool. But what makes it so tough? Well, it has all of 3 weaknesses to Water, Rock, and Steel. Why is that a good thing? Beetelord is a Walling Master. Torkindle and Armofrost certainly outclass it but Beetelord is a tough Physical Wall to beat. On the other hand, its Water weakness is well exploited because of Average Sp. Def. Speed was, A Beetelord is basically a Beetle the size of a garbage truck...it's slow. It's Really Really slow. So how else does it manage? Godly Attack Stat rivaling Scizor is unquestionable. A well tossed Earthquake can total its Steel and Rock Weaknesses...just watch that Water Weakness because Beetelord's only counter for them is Giga Drain which it gets little use of thanks to horrid Sp. Atk. It comfortably slides into the UU tier, though if used properly is usable within Standard.
Next up is for the 19th. Flirus is the Spotlighted pokemon for the day. Well, to be brutally honest, it's just a slightly better off Yanmega. Its base speed is way high but its as fragile as a sheet of paper...Physically anyway. Its Sp. Def is tolerable. Its offensive stat lies in its Sp. Atk, again outshining Yanmega. Its Physical Attack is pretty good too. But here's where it suffers. Bug/Flying typing. While generally annoying to try and hit, its typing is just awful. Bug/Flying comes packed with weaknesses. It has a good movepool and all but still not too impressive as a Steel Type (Specifically Magnezone with Lock On) can annihilate it.
For the 20th I have Dolphissure. You'll likely hate me for this but Dolphissure is a nuisance to fight. It'd definitely be a sold OU/Standard pokemon tier wise. Its stats Scream Sweeper with good speed having evolved from its previous slowness curse and the same devilish Attack stat. Its got great Sp. Def and good Defense. Its HP is rather large, it's just a well rounded pokemon. Its abilities of Hydration and Superluck are nice and its movepool is terrific. Water/Ground typing is also a blessing, paired with Ice Beam. Agility, an egg move but a useful move in general, ups its already good speed so it can set up an ice beam to get rid of Grass Types (be careful with Jumpluff and Sceptile who'll get to it before it can). But the once thing it has for that is that sizable Sp. Defense and HP making it the wonderful Water type pseudo/mini-Bliss. It more than likely won't be beaten in less than two or three hits.
21st brings forth the fossil pokemon of Rock/Steel typing, Stegnisord. Stegisord is the more Offensive of the two as Kabutops over Omastar or Rampardos over Bastiodon or Armaldo over Cradily. Stegisord is, however, doubly cursed. Fighting Types and Ground types murder it. It can outspeed most of its weaknesses but the pretty little diference maker is its ability, Solid. Its ability to suck up physical attacks repeatedly without damage is lovely (of course this only happens once down to 1 health.) But it leaves its Weaknesses in the dust, completely dooming them. How? its already Monster attack plus a Swords Dance, allowed by its ability, becomes epic. Its speed pretty much lets it outclass all of its weaknesses. A well placed Earthquake or something of the like can put its weaknesses to shame. The guy very well slots into UU and Standard if used right.
22nd has Xuant, one of two Ice/Fight types, in the spotlight. Xuant, the female of the Fire and Ice fighters, isn't as Physically inclined as its "brother", Huoant. Its stats give it a slightly lower Physical Attack and Defense Rate in exchange for the Speed and Special stats that its other lacks. This is both good and bad. Its Sp. Atk is Higher than its Physical and Ice is a good type to utilize this. Its stats actually work well with its typing, unlike Huoant. Its typing, itself, isn't terrific. Flying, Fighting, Psychic, and Fire are all Weaknesses now. Three of which have pokemon that are generally able to outspeed it. Xuant slots perfeectly into the Borderline tier as its better that Huoant in certain ways but worse in others.
23rd is Huoant, the Brother pokemon of the two. Huoant isn't as well off as Xuant but it can manage. Fire Punch and Blaze Kick generally let it outclass Xuant thanks to its larger Physical ability. But its lower special ability allows Xuant to take advantage of its ability to learn Water attacks such as Surf and Water Pulse. Huoant doesn't have nearly the speed or HP, not to mention the Special ability to keep up. Xuant just got the better end of the agreement. Ability wise, it shares Sibbling Rivalry with Xuant which ups their power when they're together. Regardless, it slots well into the UU tier.
24th. Totemyth is my favorite pokemon of this game. Its got the Rock/Psychic typing which isn't ideal really, with weaknesses to Steel, Water, Grass, Ghost, Dark, and Bug. But what makes it stand out is its Specialty attack set up exlusive to this pokemon. Separate, Rearrange, and Face Attack are wonderful. Separate is the best because Totemyth breaks down into 4 pokemon (sort of). If you use Face Attack after Separat, its a 4x attack, each strike more powerful than the last like Double Kick times two. And it ALWAYS hits that full 4. If you use Face Attack without Separate, and instead used Rearrange first, things would get interesting. The Face at the bottom is where the attack comes from. Depending on the face, that attack changes type between Grass, Fire, Water, and Electric. Stat wise, Totemyth has two outstanding Defensive Stats and a wonderful Special Attack with Passable Physical Attack and low spee. It slides right on into the bliss of Standard tier.
25th. Armetreo is terrific. It's a meteor pokemon. That said, it's a Rock/Fire type which, yes, does leave it with two almost totally unfair weaknesses to Ground and Water. Why is this nothing to sneeze at? For starters, it has terrific Special Defense and HP to cover up water types and can generally handle Ground Types. Its quick access to Sunny Day and Solar Beam makes for a wonderful counter to both. Its Speed is one that Rivals Jolteon and its Attack stats, both of them, are great. Armetreo only suffers from occasionally not being able to water Ground types which, yes, are common in Standard, forcing it into the abyss of Borderline tier.
26th. Aerocket is one of the four BEASTS of Shuinn, right up there with Armofrost, T-Lectric, and Toxber. It looks as thogh it should be a Steel/Dragon type but it isn't. It's the much appreciated type of Steel/Flying instead as steel Dragon, as we've seen, didn't do anything but swap the two weaknesses of dragon for two of the Steel Weaknesses. The Steel/Flying type has Fire and Electric Weaknesses. Aerocket can manage with its speed which is just shy of Speed form Deoxys. It, unlike Skarmory, has Earthquake to ruin its weaknesses. Also, being the shuttle pokemon, it has acces to several attacks that Skarmory doesn't such as Flamethrower. Its stats are great with Monstrous Speed and Physical Defense as well as insane Physical attack. But it has a slightly below average HP stat and average Sp. Atk and Sp. Def stats. Built to be a Physical Wall or Sweeper, expect much out of Aerocket. OU/Standard tier all the way.
27th. Hehe. You guys hated me for this. I can tell. Tentakraken, the evolved form of Tentacruel because I wanted one...and because it desperately needed it. Tentacruel was very unimpressive. Its stats were all about Sp. Defense. This time around, that remains somewhat true. Its Sp. Defense is now a monster base 200 and its nice base 100 speed now staning at 115 but its offensive stats, whoa momma. They decided to catch up. Base Physical Attack at base 110 and Base Special at a whopping 132. Tentakraken was everything Tentacruel could have wished for. The Destruction ability is pretty terrific as well while at the same time can be a doom spell. If its health hits 1/4 or less and it survives, it completely ignores the Trainers' Orders and attacks how it pleases. The catch is that the power of all of its attacks is doubled. So where does Tentakraken slip into Tier wise? I'd love to say Uber or Standard but that Ability is not going to be well liked so more likely that not, Borderline or the bottom edge of Standard.
28th. Faerest, having evolved from Faelora, isn't that great a step forward. It's evolved from a Grass/Bug type to a Grass/Ice type, keeping the weakness to fire but also gaining quite a bit such as two good counters to Ground Types, an a way to beat out Dragons (Flygon and Salamence) should it manage to outspeed them. The typing isn't terrific but the pokemon isn't bad. Nonetheless, it is a UU but a good one. Its stats are balanced enough. It has wonderful HP and okay defensive stats as well as okay Offensive stats. Its Speed is good but nothing to be afraid of. What you'll mainly want to be aware of is its movepool of Status moves and its Access to Grass Knot, Ice Beam, and Water Pulse. Grass Knot is only a problem to the steel types that think they can take it on. Steel may resist grass but Steel types are HEAVY. Ice Beam clears Dragons and Ground Types while Water Pulse Takes care of Fire and Rock types. Not to mention, thanks to its ability it only takes half damage from Special Attacks (not like it matters because only one of its weaknesses is packed with special moves) and does DOUBLE the damage with Special Attacks of its own while the opposite can be said for Physical attacks.
29th. Oh goody, the last of the 4 BEASTS, T-Lectric. T-Lectric is one scray pokemon. Dragon/Electric is a pretty scary type considering it can nearly every type. Thanks to its specific movepool it CAN cover ever type through use of Dark Pulse and Brick Break to get the Ghost, Dark, and Psychic types. Its ability isn't unlike Tyranitar's ability to summon up a sandstorm. But T-Lectric summons up Lightning Storms. It's useful for clearing Flying Types and Water Types. Stat wise, it's the best off out of the four with two insane offensive stats, goliath defense and good special defense, scary good speed (Aerodactyle rival) and average HP. Tier? Standard and if cards played right, Uber...that's right, Uber.
30th. Empressect is the new Bug Queen on the block. While its typing is awful with a similar composition to that of Celebi, it’s actually worse off with more weaknesses and less coverage. BUT it makes up for this with a nice little ability and a good set of stats, placing it into the UU tier rather than NU. Its stats, barring Speed, are all outstanding. HP is massive, both defenses are monster, both offenses stand at 110 a piece. It’s not in the least bit a shy little bug pokemon and its ability boosts the power of its own moves as well as those of other Ant Pokemon. (not including Paras, Parasect, or Trapinch)
31st is the wrap up of this list. Unequin is a unique pokemon of the Fire/Ice typing. That is wonderful actually. Fire keeps all of its weaknesses but Ice loses two of its weaknesses. Combined with Ariel Ace and Water attacks, Unequin can cover all of its weaknesses. Its stats have taken to its liking. Its speed remains at a monstrously high level as its offensive power has been swapped. Sp. Atk now being hight that physical attack. Its defensive stats aren’t terrific but this Special Sweeper is very affective. Tier wise, it’s pretty strictly stuck in UU but it’s a good pokemon there and can manage to scrape the bottom of the OU barrel occasionally.