Well, you've got some decent ideas but I don't really agree with them so I feel like posting my thoughts.
I think Shellder and Tirtouga should be switched. Every time I've used Shellder, I've always been disappointed. You have to either give up Icicle Spear which now means bulky Grass types easily beat you, or give up Razor Shell which means you can't touch Steel types. Tirtouga on the other hand has fantastic coverage with just its STABs: only Croagunk and Ferroseed resist both. The SturdyJuice Smash set I'd agree isn't as good as it used to be - Solid Rock Shell Smash with Eviolite is what I run personally, and it never disappoints.
I get where you're coming from but I'm not so sure about this. Let's start with the premise you're never giving up on Icicle Spear since it's Shellder's best attacking move. The choice you have to make is between having a priority move in Ice Shard or a strong stab to hit Steel types, you can choose the one which fits your team the best. The fact that Shellder can have a really decent physical bulk to set up in front of a lot of physical mons is really important, as much as the ability to hit hard multi-hit moves, which lets Shellder break through Sashbra and getting some rolls due to how rolls work in LC. When you say that without Razor Shell you can't touch steel-types you're kinda right, although the only relevant steel types which resist both ice and rock-type moves are only Pawniard and Magnemite. Another point for Shellder is its pure water type, which leaves it with only 2 weaknesses and no x4 ones.
Tirtouga has a great moverpool and sturdy + berry juice, but it lacks of power enough to beat what it wants to. The fact that only 2 mons resist its stabs doesn't mean it has only 2 counters, it is very easy to stop with foongus, pumpkaboo, mienfoo, sashbra, chinchou, timburr and any 17 speed scarf mon (+ croagunk and ferroseed), though I'm sure I'm leaving some mons.
In conclusion, Shellder is better than Tirtouga. I also recommend reading
this post for more information.
Rufflet I think could be C+, maybe B-. It's much bulkier than Taillow and Fletchling, can hit hard without recoil unlike Doduo and has access to Superpower, meaning it's one of the few birds in LC that can smash straight through Pawniard and Berry Juice Tirtouga.
I get your point but personally I find it outclassed by any other bird and Superpower ohkoing pawniard is like its only niche. I think it's fine where it is.
Anorith I think could be C or C+, as it's the fastest Stealth Rock setter in LC (bar Diglett who'd prefer to have Substitute or Memento in that slot) and hits pretty hard too. Unlike Drilbur, it can also get through defensive Archen and Vullaby, and it packs Knock Off so you can lure in bulky Fighting types and remove their Eviolites. Seriously underrated Pokémon.
I completelly agree with this, Anorith is really underrated and it's really good in the current metagame.
Elekid - C+ IMO. It is very fast, but it's extremely fragile and not that powerful. Priority makes it harder for Elekid to do its job.
Elekid is awesome in the current metagame. It hits 20 speed which means it can run LO to mitigate its weakness while still outspeeding a lot of things. Elekid has a huge moverpool (Thunderbolt/Volt Switch/Psychic/Cross Chop/Hidden Power (whatever, generally grass)/Ice Punch, Substitute...) and it's one of the biggest anti-meta mons nowadays. It destroys balanced teams and has a good time against offense, 2HKOing every switching-in mon. It definitelly deserves to stay if not raising.
Shellos. Is Sticky Hold really that good?
Yes, it is. It is a good choice for a bulky water with such a good coverage move options and a reliable recovery move in Recover. It's a nice choice for most of semi-stall teams.
Frillish - B-. Great bulky spinblocker, and unlike Slowpoke and Shellos it can do decent damage thanks to STAB Hex (when you're throwing around Scalds and Will-O-Wisps getting the enemy statused is not difficult). It can also run a Scarf set with Water Spout, although I personally think Wailmer and Remoraid do that better. It can also check dangerous Pokémon like Shell Smash Omanyte.
Frillish is generally outclassed as a bulky spinblocker by Pumpkaboo which is just better, and as a bulky water by a lot of mons like Chinchou or Slowpoke. It's niche is being in the half of the way, but being Knock Off weak for a defensive pokemon in Little Cup is too big. The offensive version isn't good enough to deserve B-. It should stay as well.
I hope I didn't make any mistakes but excuse me just in case, it's been a long time I didn't make a long post X)