Can't get Imgur to work at the moment, so I'll upload the pictures later---however this line is popular enough I imagine everyone knows what they look like.
#182 - Marill
Water/Fairy (Water Prior Gen VI)
All hail the PokeGod, Pikablu! Yeah, here's another super-popular Generation II pre-release Pokemon that was hyped up back during the early 'net days of Pokemon's popularity as an extremely rare Pokemon hidden within Red and Blue that could be caught via numerous elaborate cheat codes and was deemed "Pikablu" due to its resemblance to everyone's favorite electric rat. Then Gold and Silver was released, and the Pokemon known as was Pikablu was actually called Marill and a pretty standard Pokemon with no explicit relationship to Pikachu though some fans still consider it the Pika-Clone of Gen II. If you ask me, I see it as a counterpart to Jigglypuff, especially post-Gen VI where they now share a Type. Despite all the hype leading up to its release, Marill was extremely sparse in Gold and Silver and only appeared in one location with an encounter rate of 1%, unless a "swarm" occurred. You see, Game Freak thought it'd be a good idea to make a handful of new Pokemon basically unavailable unless an in-game character called you up on the PokeGear, which you had no way to influence, and told you about a swarm, after which you'd need to drop everything and rush over to that location within 30 real-time minutes or else you'd miss your chance to catch that Pokemon with ease. It was a pretty dumb method, and meant very few people got a chance to use Marill during their Gold and Silver adventure---thankfully, in future games Marill became quite more common so it didn't fade into complete obscurity. Water-type Pokemon aren't rare by any means (though now it's the only Water/Fairy ever), so missing out on Marill probably wasn't a big deal---in Gold and Silver it was pretty uneventful and not too exciting to use. Marill was one of the first Pokemon revealed to become a Fairy in Generation VI, which surprised a bunch of folks since there's nothing particularly Fairy-like about it except being cute, and I think made a lot of folks doubt the necessity of a new Type if seemingly random Pokemon were going to be turned into it without any real reason. Though it turned out for the best for Marill and its evolution...
Marill's basically a stereotypical mouse (and actually looks like one unlike Pikachu), and is interesting as a Water-type Pokemon since it's the first one not explicitly based on an actual aquatic creature, instead it follows the pattern Fire-type and Electric-type Pokemon tend to follow, where a "non-elemental" creature is slapped with the Type and colored to suit it. Throughout the history of Water Pokemon, there are like six or so who aren't naturally aquatic creatures, though some might say Marill might be one of the various species of "water rats", but personally I think they were just going for "mouse who is Water-type". Marill's pretty cute, but it's another Pokemon who I recognize as cute, but don't find it particularly endearing because it doesn't have that quirkiness I tend to enjoy.
Though Marill might just be a "Water-type mouse", it has an additional motif in its tail which is basically its own personal flotation device, filled with a special oil that helps keep Marill afloat. Unlike most Water-type Pokemon, who seem to presumably be capable of surviving indefinitely in the water without the need to surface for air, Marill in particular is said to be capable of drowning and thus depends on its tail to help keep it afloat. Despite the fact it uses what amounts to a life-jacket, Marill isn't a poor swimmer, as its special water-resistant fur allows it to swim at great speeds through the strongest currents, though you wouldn't get that impression looking at its abysmal Speed. Marill's a pretty normal Pokemon otherwise, all of its abilities explainable through regular biology, so once more it's surprising Generation VI implied it had some sort of special "fairy powers" since there was no indication of this before. Though as I'll explain later, I think the Fairy-type was given to Marill with its evolution in mind more so.
Marill made its grand debut in Pikachu's Vacation, and since then has appeared throughout the show's run in numerous roles, but I'll list the most important here for time. First, it was a main cast member during the Orange Islands season under the command of Tracey Sketchit, so of course it was totally pointless and its greatest accomplishment was getting knocked up. I'm not even joking about that. Second, another one became a temporary main character in Diamond and Pearl when Lyra, the HGSS female player character, joined up with Ash and Co. during a couple episodes. And finally one of the reasons I consider it a Jigglypuff counterpart, the ANA Marill. When the Pokemon movies stopped having Pikachu Shorts starting with Destiny Deoxys and continuing until they were brought back for the Keldeo movie, there were four special "Pikachu Shorts" that aired on All Nippon Airline flights and were later released on DVD. In these, there was a reoccurring Marill who basically copied Jigglypuff, Singing everyone to sleep and then getting pissed off. So, yeah, that's probably the moment for me I started to think of Marill as a Jigglypuff counterpart, though there were other reasons of course.
#183 - Azumarill
Water/Fairy (Water Prior Gen VI)
At Level 18, Marill evolves into Azumarill. Originally, Azumarill wasn't too special, and since you couldn't use one without getting a Marill first in Gold and Silver, most folks probably skipped it over during the main adventure. Azumarill had decent defenses and HP, but meager Attack and Special Attack, and not a lot of moves to work with, though Belly Drum helped it out a bit and it was pretty decent in the competitive scene. Since then, though, Azumarill has steadily gotten better in each game, and nowadays is considered quite powerful. First came Generation III which gave it Huge Power, an Ability which doubled its Attack to usable levels. Then Generation IV's Physical/Special split happened, and gave it actual Physical Water-type moves to use alongside its bolstered Attack. And then came Generation VI, giving it the Fairy-type which gave it additional resistances and an immunity, turning it overnight into a Dragon-slaying machine! This is one Pokemon I never believed would be considered capable of dealing with some of the most powerful Pokemon in the game, but here we are. I imagine many folks playing XY and especially ORAS, where the Marill line was readily available, probably gave this line a shot during the main adventure to see what they were now capable of.
Here we go from mouse to rabbit, but compared to our last Pokemon family this is a rather "Generation I" evolution despite the change in species. You could convince me Marill was based off an aquatic mouse, but as far as I know there's no rabbit that specializes in swimming, so once more this seems to be a classic "regular animal + Element type" Pokemon deal. I kind of wish we had more Water-type Pokemon like this---not every Water-type Pokemon needs to actually be capable of swimming in my opinion, and I'd love more terrestrial animals who simply have control over water rather than actually live and breathe it. Azumarill brings to mind Wigglytuff, and the main elements that changes from Marill are its longer ears, very sensitive and capable of searching out prey in the loudest rivers, as well as cute white spots that resemble bubbles foaming up which it uses as camouflage. I think I honestly like Marill a bit more, but both Pokemon are solid designs overall and I have no ill-will towards them. Their pre-evolution though...
While Marill relied on its tail to support it, Azumarill seems to be much more capable on its own as it's able to store a ton of air within its body meaning drowning isn't a problem. It has since become the "Life Guard" of the Pokemon World, so to speak, as it will actually assist drowning Pokemon by creating a special air balloon that provides a troubled Pokemon, or human I imagine, with air which is pretty nice of it. So, like Wigglytuff, Azumarill seems to have a similar balloon-like body, and it's another reason I associate the two lines together. By the way, I've always been confused as to why Azumarill learned Huge Power, as it didn't really seem to fit its design or personality, but I'm pretty sure now that it's an untranslatable Japanese pun---its original name is "chikaramochi", which translates to "Muscleman". You might be like, wait a second, why does a cute rabbit have an Ability called "Muscleman?" Well, the "mochi" part can also refer to a special rice cake in Japan which is said to be created by rabbits on the moon, and Huge Power happens to be learned by Azumarill's family, a Generation VI family based on rabbits, and a Mega who has rabbit-like ears, so I'm pretty sure I'm on the mark here. There's a Yokai Watch character who also does a pun off the "mochi" part of "chikaramochi", though it is actually made of mochi. So, yeah, Japan loves puns. You know, I wonder if this was the reason behind the Fairy-typing due to the relationship between rabbits, mochi, and the moon?
Azumarill has a lot of minor appearances in the show like Marill, but it's never really played a major role as a member of a main character's team, the closest is being a minor Pokemon of Jackson's in the Johto League, which went down quickly to Pikachu, and being used by Paul in Diamond and Pearl, who released it after it lost a fight against the Rock-type Gym Leader. If only Paul knew what it was actually capable of, he might reconsider. Its focus episode in Johto was a rather cute one where Ash's Totodile fell for it, but of course it already had a Golduck boyfriend leaving the poor alligator Pokemon out of luck.
#298 - Azurill
Normal/Fairy (Normal Prior Gen VI)
Generation III was for the most part a new start for the series, however there were two Baby Pokemon introduced with ties to previous Generation II Pokemon---Azurill is one of them, and a Pichu-tier Baby in my opinion who wasn't really needed. It feels like Marill didn't end up being as popular as Game Freak had hoped, but then they're the ones who made it difficult to actually use in Gold and Silver, and thus introduced a Baby for Marill to try and salvage the Pokemon's popularity. I don't think anyone was excited to see Azurill, and while Marill and Azumarill did sort of regain their popularity thanks to various factors, I don't think Azurill played a part in that. Azurill is odd because it's not a Water-type Pokemon, but rather a Normal-type, and also is 75% female as opposed to Marill and Azumarill's even 50/50 split. This actually means that in Generation III through Generation V, an Azurill could actually switch gender upon evolving! I imagine this was a mistake, and a popular theory I've heard explaining both this and its Normal-typing was that the data for possibly Igglybuff got mixed up for Azurill, and no one caught it before the game was released. I'm not sure if I believe this, but it sounds plausible---I mean some folks still think Game Freak fudged up the evolution lines of Venonat and Caterpie, this doesn't seem too crazy. The only issue with it being accidentally typed Normal is that it was a pre-release Pokemon, so you think someone would've noticed, but I don't know if its Type was ever actually mentioned prior to release so I can't say for sure when it became a Normal-type. Also, I really dislike what they did with the names here, going from Azurill, to Marill, and then back to Azumarill just gets confusing.
Though Azurill is blue like its evolutions, it isn't a Water-type, and is said to live near water but presumably isn't capable of swimming yet. I don't really know why they made it Normal-type for this reason alone, if it wasn't an accident, since I think it still could've been one due to its association with water and learning Water-type attacks, but that's what Game Freak did. Azurill is so small that its tail not dwarfs it, and it's often seen sitting atop it as well as bouncing around. Furthermore, the tail can be thrown like a lasso to propel Azurill forward, fight off larger enemies, and as the depressingly short HG/SS PokeDex entry tells us "its tail is packed full of the nutrients it needs to grow". It has a cuteness to its lore, and I think the way they used the tail in a new way for the Baby is creative enough to save it from being completely dull. Though once more, did anyone really wonder what a Baby Marill looked like?
Azurill's admittedly pretty adorable, and despite my feelings about its purpose I've grown to like it a bit more along with the rest of the line over the years, but the question I still have is why does the Sugimori Art show it being absolutely terrified and upset? Everywhere else it tends for the most part to be a very joyous Pokemon with a positive attitude, but in the Sugimori Art it looks like it's about to be killed. It actually sort of detracts from the design in my opinion when it's frowning, as it's best attribute is being cute, and seeing it distressed really isn't cute unless you're into that sort of thing, which you shouldn't be in this case since we're talking about an underage Pokemon. This reminds me how disappointed I was that the Ruby and Sapphire Pokemon didn't get new Sugimori Art in ORAS like how Kanto and Johto Pokemon did in their remakes. I guess the Hoenn art was recent enough and was close to the modern style that it didn't need to be changed, but still I'd like to see updated art just to have some new stock art to look at.
Azurill made its grand premiere in Pikachu's PikaBoo, and made its first in-show appearance in the second episode of Hoenn where May unsuccessfully tried to capture one. Misty later obtained one in the Battle Frontier season, and it was actually the child of Tracey's Marill---yeah, there was an awkward time where the show seemed to be shipping Misty and Tracey. It's never been said who the father was, but most folks assume it's one of Misty Pokemon, and going by Egg Groups, it could be either Politoed, Psyduck, Dewgong, Horsea, or Corsola. Most people like to think it's Psyduck.