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1. Can shapeshift into another Pokémon
The only other Pokémon capable of doing this are Mew, Zorua, Zoroark and Smeargle (when copying Morphing with his signature move Sketch).
Ditto
Shuckle
Iron Jugulis
Gardevoir
2. Possesses an IQ of 5000
The Pokédex says that Metagross' intelligence is compared to a super-computer but it's Alakazam who has an IQ superior to 5000.
Metagross
Alakazam
Hypno
Slowpoke
3. Is only male
Glalie can be either male or female, unlike Froslass who can only be female. It's the opposite for Gallade who can only be male whereas Gardevoir can be either male or female.
Glalie
Machamp
Gallade
All 3 of them
4. Evolves with a Thunder Stone
Flaaffy evolves at level 30 and Elektabuzz evolves with an exchange while holding an Electirizer.
Flaaffy
Elektabuzz
Tadbulb
All 3 of them
5. Is a Legendary Pokémon
Arceus, Darkrai and Zeraora are mythical Pokémon.
Cresselia
Arceus
Darkrai
Zeraora
6. Is a Water-Type Pokémon
Dragonair is a Dragon-Type Pokémon, Lugia is Psychic-Flying, Kabutops is Water-Rock and Azurill is Normal-Fairy.
Dragonair
Lugia
Kabutops
Azurill
7. Appeared for the first time in the eighth generation
Sirfetch'd and Falinks both appeared in Sword and Shield, Ursaluna first appeared in Pokémon Legends: Arceus, three games in the eighth generation.