Alolan Rattata
Thick Fat is pretty useless on a Pokemon with Rattata's defenses, so Hustle is what we got. I am of the opinion Hustle is a terrible ability, this Pokemon would be way better if it still had Guts.
Alolan Sandshrew
Ice/Steel seems like a bad typing, but Slush Rush is a very good ability. Ice is a solid offensive type but when your best physical Ice move is Ice Ball there is a problem. That is probably the biggest issue here actually. The 4x weaknesses do it no favors, but if it got Icicle Crash it would be way better.
Alolan Vulpix
Ice Vulpix is not nearly as strong as its Fire counterpart. STAB 100% accuracy Blizzard is nice but the Sun-boosted Fire attacks is kind of what gave Vulpix it's power. It is a shame it doesn't get Energy Ball and Will-O-Wisp anymore. It does learn Heat Wave though, which is kind of fun. It will be a decent Ice-type, but lacking the power to really shine.
Alolan Diglett
Still takes hits like tissue paper, all the Steel-typing does is make Mach Punch and Vacuum Wave hurt more. A Gooey clone on one of the fastest and frailest Pokemon in the tier? Okay.
Alolan Meowth
Now we're talking. Regular Meowth was already an okay Pokemon, but I think Dark-type Meowth is a direct improvement. The loss of power of Fake Out is noticable, but STAB Bite and Thief boosted by Technician! Aerial Ace will help with Fighting-types too. A good Dark-type I am excited to try out.
Alolan Geodude
Taking neutral damage from Steel-type moves and being weak to Ground and Grass kind of hurts its ability to trap most of the common Steel-types. However, the Hidden Ability is pretty ridiculous. Sure, it can't hit Ground-types at all, but 80 base Attack Galvanized Return? Double-Edge? Explosion? The typing itself has defensive issues and that Speed is way too low, but Alolan Geodude will be fun at least.
Alolan Grimer
LC Doubles probably isn't going to take off, so the Hidden Ability isn't worth talking about. STAB Knock Off is good, Poison Touch makes it better. Poison/Dark is a pretty solid typing and Grimer has good stats. I can see this Pokemon getting some use for its defensive typing. Its lack of recovery outside of Rest really hurts.
Rowlet
An underwhelming Pokemon with an underwhelming movepool and underwhelming stats. It might be a decent Defogger, but outside of that all its good for is smacking Rock-types and Chinchou on a BirdSpam team. And even then I don't see it excelling. I wish it got something to make it a little more impactful.
Litten
Litten is definitely the strongest of the new starters and the only one with any substantial viability. Intimidate, Will-O-Wisp and U-turn are very nice, despite its terrible defenses. It has good Speed and offensive stats, backed by Swords Dance AND Nasty Plot, but these seem like red herrings. We will probably see a little bit of Litten for its utility potential and not as a sweeper.
Popplio
Popplio's strength is going to be largely dependant on how its Hidden Ability works. Until then, it is just another pure Water-type with a good Special Attack and not much else, and will likely end up in the same pond alongside Psyduck, Oshawott and others.
Pikipek
Pikipek will fit well on BirdSpam teams, although nerfs to Fletchling are not doing favors for BirdSpam, for its ability to Bullet Seed and Brick Break down many Pokemon that give that archetype trouble. Those defenses are very unforgiving though and it will need to be careful switching in. Pikipek definitely has potential and I can see it doing well.
Yungoos
Exclusively a Choice Scarf user, but a very scary one. It has a good Attack backed by three amazing abilities. It also has U-turn, which is the icing on the cake. This Pokemon is a glass cannon and will require both players to play very carefully around it.
Grubbin
Know how much use Karrablast gets? This Pokemon is basically a worse Karrablast. That should give you a good idea of what to expect.
Crabrawler
A pretty cool Fighting-type that will unfortunately be overshadowed by other Fighting-types. Crabrawler is a solid Pokemon, just not enough compared to the likes of Mienfoo, Timburr, Croagunk, Pancham and Scraggy. Would be much more comparable if it got Knock Off and Drain Punch.
Cutiefly
Hitting 19 Speed is amazing by itself, but the addition of Quiver Dance and Baton Pass kicks ass. Sadly its stats aside from Speed are pretty mediocre, but it could still be a pretty threatening sweeper with Quiver Dance and Moonblast. Shield Dust is also an underappreciated ability. It will be a good Fairy-type for more offense-oriented teams.
Rockruff
A below-average Rock-type. It reminds me of all the bad things about Cranidos without any of the good.
Mareanie
It has good defenses, a good typing and Regenerator. However, its support options seem pretty limited, and its power is lacking. It will likely count on using the likes of Scald and Sludge Bomb to 30% its way to victory, do some Recovering as they suffer and Regenerate a ton of health as it switches around the enemy team. Annoying, but not overwhelmingly threatening.
Mudbray
A solid Choice Scarf user, it has high Attack, good defenses and a solid ability. Probably overshadowed by Drilbur, but a strong Pokemon by itself. Could also use Berry Juice to pretty good effect, especially alongside Stamina.
Dewpider
Changes to Leech Life help, but not by much. Water/Bug is a decent offensive typing, but it is simply much too slow and too weak for an offensive set. Defensively, it has good Special Defense but its other stats are nothing to write home about. Probably won't see much use in the long run.
Fomantis
This Pokemon is a bad Snivy.
Morelull
A pretty sweet Pokemon to be honest. Its abilities are pretty useless, but Spore is good and Strength Sap sounds ridiculous. Leech Seed is a nice option as well, and it has a decent Special Attack for Giga Drain and Moonblast. Its HP is a little low, but its Defense is okay and its Special Defense is pretty nice. This Pokemon will probably see use and might even give our current resident mushroom a run for its money.
Salandit
I don't know why they would give Corrosion to such an offensive Pokemon, but whatever. Nasty Plot boosted Sludge Bombs and Fire Blasts will hurt and it has pretty good Speed too. Salandit will definitely see some use and be a solid sweeper. A no-frills kind of Pokemon, despite the unique ability.
Stufful
I honestly have no idea about this thing. Stufful has an awesome ability and good stats, but LC has a lot of good Fighting-types. Will Fluffy be enough to carve out its place among the elite Fighting-types, or will it be overshadowed by old threats? I honestly don't know.
Bounsweet
It looks like Cherubi and, judging by those stats, moves and abilities, will likely be just as useful.
Wimpod
Seeing Wimpod is like when your professor says that the class average for an exam was a B and you get yours back and you got a D+.
Sandygast
Honestly this might be the Pokemon I am the most excited about. Ground/Ghost is a really cool typing and this Pokemon has an amazing ability, access to recovery in the form of Shore Up, good Special Attack and a very interesting movepool. Not getting Will-O-Wisp breaks my heart, but I think this Pokemon definitely has potential.
Type: Null
Incredible stats, this Pokemon will be top tier, if not incredibly broken.
Jangmo-o
Kind of looks like a weaker Axew with an awesome ability in the form of Bulletproof. 55 base Attack seems a little low for a Dragon Dance sweeper, and it can't hit Fairy-types. A cool concept held back by its BST and movepool gaps.
"Cosmog"
Shut down by Taunt, 0/10