Carnage always take a group of heroes to down
Electro has incredible potential but prefers to lay low and do grunt work (and so does the rest of spidey's enemies)
Sandman has proven to be smart and holdd the entire Fantastic Four on his own
Oldschool Doc Ock was top tier mad genius scientist with world domination plans.
Kingpin is nearly untouchable.
Kraven is king and currently immortal and a great warrior.
Osborn is a billionaire with great power and influence
Most of them are obsessed with Spider-Man andmonly face him, when they could easily succeed against other heroes.