
Ratattatattatatta. Pidgey is the most basic of birds, and Ratatta is similarly the most basic of mammals. It’s exactly what it says on the tin; definitely a rat – albeit one slightly less chubby and cute than (domestic) real-life rats, which is backwards from Pokémon’s usual M.O. It’s also a pale purple, which is something the Pokémon games will regularly use to denote potentially poisonous monsters, but not in this case! It’s as normal as a Normal-type gets: take a dirt-common animal and abstract it a bit, even with a cute little curled tail to give it a modicum of character appeal, and… whiskers that appear to be part of its flesh? Let’s not think about that too hard. Not half-bad for an ankle-biter.

Raticate, Raticate, baker’s man! He’s rounder and better-fed now, plus his coloration is down to a drab brown and his fur looks a bit unkempt, plus his tail is naked. You’ve got both sets of long teeth in there instead of just the cartoon buck-teeth interpretation, too. In short, he looks much more like a proper rat now and less like a monster just inspired by one. He looks less ready to pounce on you now, though, and more kinda like someone’s pet that hasn’t been groomed in a while. Cute in its dirty little way.
Bonus round for the variants introduced in Sun and Moon!

Not much to write home about difference-wise; it’s a slightly scruffier, darker-furred Ratatta, which is a very basic way of illustrating that it’s Dark-type now. Apparently it’s a reference to rats being more aggressively invasive in Hawaii, which is the geographical analogue for where this subspecies shows up. Can’t get over its dumb lil’ mustache here.

Even more scruffy and overfed than the original – just look at those puffy cheeks. It’s the island take on Ratatta, but applied to Raticate’s design and underscored a bit. Nothing terribly surprising.
In the games, he’s a strong early choice for getting basic moves that hit hard and fast, but he doesn’t have any outstanding points or much variety to him and so he’ll fall out of favor with most people fairly early. Just kinda one-note. The Alolan variation is a bit heftier, but that’s about it. Neither one is going to set the world on fire.
The Pokémon Company knows this, too. People are aware of Ratatta because it’s kind of one of the go-to trash mobs of the first game, but it’s less photogenic than Pidgey, so you’ll occasionally see one scurry across as set dressing but rarely if ever in an advertising situation. Not even stand-out at being not-stand-out.
I want to circle back to Ratatta’s coloration because it’s such a head-scratcher. In the early games in particular (and even today), purple was used as a pretty consistent color palette for poisonous Pokémon in the same way that blue usually denoted water and red/orange usually signaled fire-types. Ekans, male Nidoran, Zubat’s wings… even the Gastly line used it as a hint that they were part-poison. You do get other exceptions, but it’s notable that one of the very first and most common purple Pokémon you find doesn’t follow the trend, which kind of bucks that through-line before it even gets going. Even more of an odd choice since Raticate goes back to a normal rat-brown.
Most of its Pokédex entries are pretty boring – just about biting things and nesting, though that does tie in to this little guy having two signature moves (Hyper Fang and Super Fang) revolving around biting things; an impressive get for what’s supposed to be the most common of common ‘mon. Unfortunately, even that’s been taken away, and since the Sinnoh-set games there have been a half-dozen more critters that can use those moves now, too.
Those nose-whiskers I find so funny on the Alolan variant might have something to them – apparently it uses those to enhance its sense of smell somehow? Not gonna pretend to understand how that works, but hey, the variation at least has something unique to it.
Un-translated name corner: the original name for Ratatta is literally just “Little Raticate”, where Raticate’s name is one letter away from just “rat”. So blatantly on-the-nose that you wonder if the designers initially treated this fella as a throwaway monster.
Which… it kind of is. Rodent-based Pokémon are kind of everywhere, and this is the most basic even of those. A bit redundant to have around when the actual face of the series is a mouse. Ratatta wasn’t bringing a whole lot to the table in 1996 – mostly just early-game filler – and it’s certainly not giving us anything new now. This is probably one of the easiest calls in the first generation to straight-up Retire for lack of interesting contribution, but something in me doubts that Game Freak would ever do that to any of the original 151, so that would be his one lifeline to Reserve status.
Any and all appreciation for Ratatta and Raticate is welcome in the comments!