-Krabby (Blue/Yellow) – High Tier
-Availability: While Krabby can be caught in its base form by fishing with the Super Rod in various areas including (but not limited to) Fuschia City, Vermilion City, and Routes 11, 12, 18, it'll only be level 15, meaning it would have quite a long way to catch up the rest of the party. In Yellow, Krabby can be found in the bottom 2 floors of Seafoam Islands by means of the Super Rod at level 35 as a Kingler. However, Kingler can be found at the B3 floor of Seafoam Islands level 39, which should be very similar in level to the rest of your team, provided you went to get it before clearing out Silph Co. While they only have a 4% chance of appearing, Repels remedy this, provided the Pokemon leading your party isn't below level 34 or above level 39 at the time. Krabby can evolve at level 28, in other words right after being caught.
-Stats: Kingler has a massive base 130 Attack, which is tied with Rhydon and Flareon and second only to Dragonite, which is almost impossible to get in-game without a large amount of grinding. Its Defense isn't too far behind, and its Speed is enough to outpace an almost all of the game's remaining Pokemon (at least those who aren't higher leveled than it). However, Kingler's weakest stat is Special, at a dismal base 50. Of course, If you settled for Krabby to get earlier access to Crabhammer, you don't have to worry too much, as it still has solid Attack and Defense.
-Movepool: Krabby and Kingler have exclusive access to the move Crabhammer, which acts like a slightly more powerful, 85% accurate, Water-type Slash, and as such is the best Water-type move in the game. As such, it makes up for Kingler's pathetic Special, and is mandatory on it. Kingler, like most other Water-types, has access to Ice Beam and Blizzard, but its awful Special means its usability outside of Lance is just as bad. Also, Kingler can learn Guillotine, which is an OHKO move and as such can make it quite useful for major battles in combination with X Accuracy and X Speed when Crabhammer and Strength can't cut it. Kingler learns Guillotine at level 25 and Crabhammer at level 42. Also, catching Krabby rather than Kingler in Yellow for an earlier Crabhammer is a definite option, as Krabby learns it at level 35. If you teach Kingler Surf and Strength, it can also act as a useful HM slave alongside its role of killing things with Crabhammer.
-Power: Against the majority of trainers, Kingler does well, with Crabhammer to annihilate anything weak to it and Strength to deal with everything else. Crabhammer and Water-typing combined with a titanic Base 130 Attack make Kingler a mixed attacker while simultaneously having perfect type coverage in just 2 moves, allowing it to hold its own against the majority of the game's remaining trainers.
-Type: While Kingler is a Water-type with no secondary typings, it isn't too bad, because Kingler's weaknesses are both very uncommon, meaning Kingler won't have much to worry about in the majority of battles as far as type match-ups are concerned.
-Match-ups: The X item + Guillotine combination will not be taken into account for these battles, as Kingler defeats everybody (with the exceptions of Agatha and Sabrina) with it.
--Sabrina: Although Strength hits her Pokemon like a truck, the majority of her Pokemon are faster than Kingler and hurt it hard due to its dismal Special.
--Blaine: Considering the fact that his Pokemon are weak to Crabhammer and the fact that Kingler can confidently take physical hits not boosted by STAB, the outcome of this should be easy to see.
--Giovanni: Giovanni is steamrolled in Red and Blue, but he is definitely more threatening to Kingler in Yellow, as both his Nidos know Thunder, meaning if they survive a Crabhammer, there's a 70% chance of it getting fried.
--Lorelei: Unfortunately for Kingler, Lorelei happens to have Cloyster, Slowbro, and Lapras: the 3 Water-types that give Kingler the most trouble, in her arsenal.
--Bruno: Kingler can take a good amount of his Pokemon's attacks and whack them hard with Crabhammer, but don't expect Kingler to take hits from his entire team, as it only 2HKOes the Fighting-types, meaning they're guaranteed to get at least one hit in, and Hitmonlee can attack a second time before going down, thanks to its superior Speed.
--Agatha: Her Ghost-types can comfortably take everything Kingler can throw at it, although multiple Crabhammers will wear them down over time. It doesn't help that her first Gengar in Yellow knows Mega Drain.
--Lance: While Kingler can withstand more than one Hyper Beam, the only Pokemon it can do large amounts of damage against without the need for TMs is Aerodactyl. If Blizzard is added to the mix, Kingler can take out some of his Dragon-types, but they're merely 2HKOes against them, which when combined with Blizzards pathetic 5 PP means it usually won't be able to defeat his 2 Dragonair and his Dragonite in the same battle. In Yellow, Lance's first Dragonair and Dragonite know Thunderbolt and Thunder, respectively, neutralizing any attempts at chilling them to the bone.
--Rival: Needless to say, Alakazam, Magneton, and Jolteon beat Kingler with little trouble. Venusaur also does this, but it would require you to start the game with Squirtle, which means that scenario is very unlikely to happen. Gyarados, Cloyster, and Vaporeon can cause trouble, thanks to their usable, stellar, and solid (respectively) physical bulk. Everything else is handily beaten.
-Additional Comments: Kingler's greatest asset is its access to Crabhammer. Because of this, Repels aren't completely necessary, as Krabby should be able to hold its own until it learns Crabhammer at level 35. Of course, the second-highest Attack stat in the game as well as possessing perfect type coverage and the ability to hit solidly on both ends of the spectrum at the same time help its cause as well.