Franchise: Pokémon

In some of it's Pokédex entries (namely Yellow and Gold), Slowbro is said to turn back into Slowpoke if the Shellder on its tail comes off. This and most of Exeggutor's entries (which states that if its' heads fall off, they will become an Exeggcute) are the only Pokémon that mention devolution.

The first 4 regions are based on real life Japan.

Pikachu has had four balloons in the Macy's Thanksgiving Day Parade. The first one (nicknamed "Flying Pikachu") ran from 2001 to 2005. The second one was a redesign that now featured him chasing a Poké Ball balloon and ran from 2006 to 2013. The third was another redesign featuring him wearing a green scarf and holding a small, Pikachu-shaped snowman, ran from 2014 to 2020. In 2021, the fourth balloon was introduced, featuring Pikachu and Eevee riding in a bobsled resembling a Poké Ball.

Pikachu is the second video game character to be featured in the parade after Sonic The Hedgehog in 1993.

The non-damaging and non-effect move Splash is a mistranslation. It's move name in Japan is はねる (haneru) which can be translated as both Splash and Hop (although usually as the latter). This mistranslation was mostly a result from the exclusive usage by Magikarp in Generation I.

This also explains why this move can be learned by non-aquatic Pokémon such as Hopip, Spoink, and Buneary for their nature of hopping and why it is disabled by the move Gravity.

In the english versions of Pokemon, there are the Pokemon "Hitmonlee" and "Hitmonchan". The English names are references to Bruce Lee and Jackie Chan.

In the Japanese version it's "サワムラー" (Sawamular) and "エビワラー" (Ebiwalar). Sawamular is a reference to Tadashi Sawamura, the one of the first kickboxers. Ebiwalar is derived from Hiroyuki Ebihara, a Japanese world-champion boxer.

Deino, Zweilous, and Hydreigon reference numbers in the German language. Ein(s) is one, zwei is two, drei is three.

In every generation there is at least 1 small legendary Pokemon with a base stat total of 600 and a stat distribution of 100 all around.

The default character 'Red' had a short cameo appearance in the Pokemon Anime as a character in a movie.

With the exceptions of Sada and Turo in Pokemon Scarlet & Violet, all main series professors are named after a type of tree.

Throughout the Pokémon series are several references to a previous Game Freak game, Pulseman. Two of the most well known references are Barry's battle theme having very similar notes to Pulseman's first stage, and Pikachu's move, Volt Tackle, also being an attack from Pulseman. In Super Smash Bros. Brawl onwards, Pikachu's Volt Tackle Final Smash shares a similar appearance to Pulseman's Volt Tackle.

Two early Pokemon designs are named 'Godzillante' and 'Gorillaimo'.
'Godzillante' is most likely based on reptilian monster Godzilla, and
'Gorillaimo' could be based on Donkey Kong or the Universal monster King Kong. Not much is known about either Pokemon. Their designs could have been developed into other Pokemon, as they vaguely resemble Tyranitar and Slaking.

Haunter's cry changed from generation to generation. In Generation I, it had a humming noise accompanied by a beeping noise. In Generation II, the beep's pitch changed to a jingle similar to a Magneton's cry. In Generation III and onwards, the beeping was removed entirely, leaving behind only the humming.

In early artworks for Venomoth, it was shown having yellow spots on the back of its wings. These were later removed.

Garchomp is known as the Mach Pokemon, which means it can go as fast as the speed of sound. Pidgeot's pokedex description states it can go Mach 2. That is twice the speed of sound. But in the games, Garchomp's speed stats are higher than Pidgeots.

Charmander may be based on a 1000+ year old misconception about the salamander.

Both Aristotle and Pliny the Elder believed that the salamander was capable of withstanding the heat of flames, and even had the ability to extinguish them. In Pliny's Natural History, the oldest surviving encyclopedia, a fairly accurate description of the salamander is followed up by claims that "This animal is so intensely cold as to extinguish fire by its contact, in the same way as ice does" (Book 10, Chapter 86). Later in the same work, though, he seems to view these supposed properties with more skepticism, claiming that "if it had been true, it would have been made trial of at Rome long before this" (Book 29, Chapter 23).

The connection between salamanders and fire persisted, however, and we can also find it in the Talmud, which briefly mentions the salamander as a creature actually produced by flames, whose blood could protect anybody smeared in it from fire. Even Leonardo da Vinci, one of history's greatest scientific minds, seemed content to echo the received wisdom on the subject, mentioning in his notebooks that the salamander "has no digestive organs, and gets no food but from the fire, in which it constantly renews its scaly skin."

The Lileep-Cradily evolutionary line of Pokemon are based on crinoids, also known as sea lilies.

Fossil evidence shows us that creatures such as sea urchins began to view the stationary sea lilies as an easy meal: many crinoid fossils from the Triassic period show evidence of teeth-marks! It seems that this is why some crinoids became motile again. Some, such as the feather stars, have become reasonably adept swimmers: not especially quick or graceful, but enough to make a break for it if things seem to be getting dangerous. Other species have been seen to slowly walk along the sea floor using their multiple arms. This gradual progression towards motility seems to be referenced in the Pokédex entries of Lileep and Cradily, too... while Lileep is stated to be immobile, numerous references are made to Cradily moving around (albeit inelegantly).

The Pokemon Metagross seems to be heavily based on the number 12. It has 12 "toes", and the X on the center of his face has 12 sides. In addition, its name contains "gross" which means 144, or a 12 dozen. It also weighs 1212.5 pounds. .5 can be written as 1/2.

The Flygon evolutionary family is based on the Antlion.

Dunsparce, and its evolution introduced in Generation IX Dudunsparce, are based on a Japanese cryptid called the Tsuchinoko. Dunsparce's Japanese name, Nokocchi (ノコッチ) is an anagram of Tsuchinoko (ツチノコ or 槌の子).

Many Pokemon are inspired by real-life creatures. Pokemon evolution, too, is based on real natural phenomena, although it has less in common with genuine evolution than it does with a process called metamorphosis.