Psychic Pokemon were absurdly overpowered in Kanto.
In the early games before the special split, Psychic Pokemon were unbelievably powerful since they were specially bulky and very offensive. Some of these Psychic Pokemon could beat entire games on their own.
Note: This list is subjective and reflects only the opinion of the writer.
Top 5 Psychic Pokemon from Kanto
#5 - Jynx
Even though this is one of the most controversial Pokemon ever, it was an amazing Pokemon in generation I. Psychic was an overpowered typing, but Ice was also one of the only ways to deal with Elite Four Lance's Dragonite army.
Jynx has gotten a lot of flack throughout the years but it was at the top of it's tier in competitive during the early years. It continues to be a solid Pokemon to get through the main story in any game that it's available in.
#4 - Starmie
Starmie was Misty's Ace Pokemon in both the video games and the anime. A fast and strong Water Pokemon that has the secondary typing of Psychic is such a great concept for the early generations.
Starmie makes for a great partner for completing the main story or even delving into the competitive scene.
#3 - Exeggutor
Exeggutor is likely the best Grass Pokemon in Kanto as well as one of the best Psychic Pokemon. This walking Coconut Tree can dish out huge damage as well as tank a bunch of hits.
Exeggutor was at the top of competitive play during generation I, and can still see play in competitive. It's ability, Chlorophyll, allows it to double its speed during intense sunlight.
#2 - Alakazam
This Pokemon is also a bit controversial, as the creator of the term didn't appreciate the Pokemon company using it. However Alakazam was the strongest non-legendary Pokemon in Kanto.
It's speed and power were virtually unmatched, allowing this Pokemon to single handedly take down the entire main story. Mega Alakazam was also a huge threat in the main story as well as competitive play.
#1 - Mewtwo
Speaking of Pokemon that could beat the entire story alone, Mewtwo is the first name on the list. This man-made demon could run through any team all alone, and it wouldn't even require a trainer.
Mewtwo is by far the strongest Pokemon in all of Kanto and is still is a menace in competitive play. Mewtwo can blow up entire islands with one attack, as fans saw in the first Pokemon movie. Mewtwo is uncontested when it comes to Kanto Psychic Pokemon.