Psychic has 90 BP, Psyshock has 80 BP. Also, most Pokemon I see have higher Defense than Special Defence. So why am I seeing Psyshock being used more often? Is it just that everyone that I saw with Psyshock are comeplete noobs in competitive battling? Or was I just wrong about the Defense/Special Defense thing? Plz explain!
It is because Psychic users are (usually) Special Attackers. This means that they can do very little damage to Pokemon like Blissey, which has massive health and Special Defence. Psyshock gets around this problem by hitting its much weaker Defence stat, while still using the users Special Attack stat.
Psyshock is used to counter Blissey and Chansey the monster special walls(also used for other walls, but these two are the worst)
It also gives dominant special types to hit defense while using their good special attack