So, what are Water-types, really?
The Purpose of the Water Type:
Water-type is a strange type, having successfully overruled its original purpose as a middle stage between Grass and Ice. In the original games, Water would normally replace the Grass-types used by the player, and be replaced by Ice-types, most of which themselves were the most powerful Water-type Pokémon. Using a pure Water-type besides the starter was nonsensical. However, because Water was versatile enough on its own, it managed to overrule this. Having access to Ice-types has also helped this.
Later generations initially tried to nerf Water, and when that failed, Water became a the "jack of all trades, master of none" type, being bulky and powerful to hold on its own, but being far too under specialized. This did not stop Water-type, as Water became the most abundant type in the game, being accessible in all parts of the game except end-game, where end-game would just reuse older species' evolved forms.
With this overruled, Water-type is now one of the secondary competitive types, alongside titans like Ground, Flying(a fellow early type that managed to overrule its weak status with its versatility) and formerly Fighting. Now with abolishment of HMs Water serves as a reliable type players can easily obtain and raise quickly to serve as a low cost backbone for their favourites.
The Aesthetic Archetypes of Water Types:
The sheer abundance of Water-types have allowed Water-types to be demarcated into three Egg Groups, Water 1 for common Water-types, Water 2 for fish based Pokémon, and Water 3 for invertebrates. However, the aesthetic archetypes of Water-types are slightly different. Water-types are predominantly Blue colored, but there are many Pink and White colored ones. Despite its name, Water-type consists of Pokémon that live in Water, not ones that covered with or composed of Water.
Predominantly composed of terrestrial Water-types based on species that live near Water rather than in water, this is composed of animals who can swim and walk. They are predominantly bipedal, as such they get Fighting-type moves.
Based on amphibians that metamorphose, they predominantly reside in Water 1, largely exclusively. They are commonly associated with Mud and Poison.
Based on fish or species that confused with fish(in the case of Wailmer and Inkay), these Pokémon are predominantly live in Water 2 Egg Group. Some are associated by Biting moves.
Based on crustaceans, they tend to reside in Water 3 and Crabhammer.
Based on species like Slugs, Octopi and others, these are soft bodied Water-types. The ones with tentacles get moves like Constrict and Wring Out. Jellyfishes, Starfishes, and man o wars are currently included in group. They tend to reside in Water 3.
Other lesser groups include aquatic birds, and water sprites.
The In-game Archetypes of Water Types:
-Early Water type, Terrestrial: Generally the earliest Water-type you can encounter in the game, this buddy requires no extra effort to capture it. They tend to be either mammalian, or amphibian.
-Early Water type, Fish: Generally based on Goldeen, these are species in 450-475 you can early with Good Rod or whathaveyou. They are not too strong.
-The Crabhammer: Generally based on crustaceans that you can gain by fishing, they tend to reside in Water 3. Crabrawler is the only Crabhammer that is not a Water-type.
-Secondary early Water-type: Generally requiring some sort of special capture method or appearing in the same way as other archetypes as a secondary option, these are two staged(generally) species that one can get easily. They tend to be in 470 something range.
-Magikarp clone: Species that start off laughably weak but become strong later on, they test Trainer's raising abilities. Tynamo is the only Magikarp clone that is not a Water-type.
-Gimmicky single stage: Species with weird encounter methods, they are either rare species, or marketable species with low BST. They tend to get popular with the fanbase. Stunfisk can be considered the only member of this group that is not a Water-type.
Water-type generally has no late-game counterparts. Just some gimmicky one stage mons and rare species.
The Stat Archetypes for Water-types:
-The Wall: Composed of species that are generally good in both sides of defense, these species are true walls with recovery options and wide array of status moves.
-The Dual Offense: Having good offensive stats in both sides, these are true dual offensive Pokémon stat moves to boost them and mediocre defenses and Speed to keep going.
-The Bulky Water: Epitome of "Master of none" bulky waters are species that can take in and dish out significant damage to wear down the opponent. A former baby of balanced teams, bulky waters now struggle in these days of specialized species
-The Swift Swim: Poor man's bulky water, these are species with little to no speciality, just some okayish stats. Their main reason d'etre is to use Rain Dance to outspeed and outdamage fellow Pokémon.
-The Tank: Generally specialized in one offensive area, Tanks are slow species with good offensive stats and defenses, but generally poor speed.
-Speeder: A poor man's version of a Sweeper. A Speeder is a Speedy Pokémon with okay stats elsewhere. They tend to be offense oriented.