Psychic is the name of a Trainer Class, of a top-tier attacking move and of one of the most exposed types in the game. The original legendary powerhouse is none other than Mewtwo, a very recognizable pokemon with a slick design who is deservedly one of the most beloved Legendaries in the series. A lot of the flavor behind the Psychic type revolves around strange and mysterious things, ranging from magical beings to extraterrestial entities. Visually its main color is Purple, but light green, pink and golden have also been featured extensively in Psychic types. Its pokemon also favor uneven physical forms (often with several eyes/heads to imply hive minds) and frail but slim body types.
Most of the abilities given to Psychic types in the Pokedex are related to Extra Sensorial Powers often found in pop fiction: there is hypnosis, telepathy, mind-control, telekinesis and prophetical visions, as well as empathy and teleportation. Some psychic types are also able to control time itself, like Celebi (because that ability doesn’t come from it’s grass typing :p ), which can be related to telekinesis and future sight as far as powers go (after all, manipulating the physical world is a way of manipulating time itself, as time exists in relation to it). This explains how Psychic types can call upon exotic powers such as Trick Room (that reverses the order of attack, somehow affecting speed), Wonder Room (which switches physical and special defense) or even Gravity (which just increases the sensation of gravity without hurting the Pokemon in range).
Psychic Pokemon are also inspired by mental states, Slowpoke seems to be in a state of absent mindness while Meditite is in deep concentration, Slowking is said to remain calm at all times. This makes it so Psychic types have personalities that are tremendously developped compared to other pokemon types, they also seem much more closer to humans as the likes of Jynx are said to have languages.
It’s fair to say that the kind of powers weilded by these Pokemon makes them particularly scary for your regular human being. The fact that Hypno can eat your dreams or that Gothirita can mind control you into becoming their friend is something of a menace that is much more disturbing that getting burn or poisoned. They have scary powers and are very alien (sometimes literally), so pound by pound I say it’s the most scary typing aside from the obvious Ghost type.
Psychic used to be the go-to type for legendary beings, since Mewtwo and Mew established that as a matter of fact. For that reason, the designs and powersets of certain Pokemon don’t seem to appeal to Psychic powers at all… It seems they randomly fell as Psychic because they had to be something. Lugia is the living example of this kind of typing choice… I guess Water sounded like too much of a boring type and mono-Flying was a bit too novel back in the day?
I’ll take a short break discussing Psychic flavor to tackle a different topic next time. Until then, have fun!