Withheld's poke theories: The source of Sabrina's Kadabra's power

Don't you think it was unnaturally powerful? The general feeling
Sabrina's mini saga gave off was that whoever has psychic
pokemon is practically undefeated. Even when Ash sent out
Haunter, Sabrina didn't seem to worry (and that was before it
turned out that Haunter did not obey Ash).
Later, in the orange league's fourth gym battle, Ash faced
Kadabra's evolved form, Alakazam, and it was nowhere near
as haxed as Sabrina's Kadabra. Mind that it evolved into a
Kadabra during the fight against Ash, which means that,
before Ashes arrival, she was a fearsome, undefeated trainer
with just an Abra!
An obvious out of universe explanation is that, at that early
stage of the series, when the writers did not know yet how
long the series would last, they didn't give much thought to
the future, so, for the sake of drama/coolness, they had
decided to present the psychic type as practically semi
legendary pokemon that could only be controlled by Sabrina,
or at most by very few chosen people with psychic powers.
Anyway, what about a good in universe explanation? Here
is mine...
As we saw in the end of the battle, when Sabrina's laughter
caused Kadabra's laughter, those two were telepathetically
connected. I think that telepathetic connection somehow
made Kadabra far more powerful than a normal Kadabra is
supposed to be, haxing it almost to Mewtwo level.

What I think is that it's meant to represent how OP psychic type Pokémon were in generation 1. In later gens, we can also see Psychic type Pokémon having great bonds with their trainers. An example would be Diantha and her Gardevoir.

Yes, it was overpowered to be honest but on the other hand I also enjoyed how Ash had to struggle. I thought it would've been such good lesson for him not to be an arrogant trainer but after it was over he didn't seem to care, lol.