This episode features not one, not two, not even three, but FOUR villains! Sort of.
Dr. Noah Boddy breaks Vulture, Electro, and Green Goblin out of prison. He decides that they should work together to defeat Spider-Man since they have all failed at this task individually. Boddy's plan involves an intentional hit and run attack by each of them. Each attack will weaken one of his powers. Once all three of them have had their turn, they will gang up for the kill, provided they don't kill each other first.
The Goblin attacks first, using a special pumpkin bomb that knocks out his spider-sense.
The next night the Vulture takes his turn. Special egg-shaped concussion bomb drains his spider strength. Electro then delivers their ultimatum: meet them at midnight for a fight to the death. If he refuses, they'll destroy the city and everyone in it. [Electro got the short end of the revenge stick.]
That night, Peter makes a new web formula for his showdown. He also makes other preparations for his final battle with his enemies.
At midnight he meets them on the docks. They make their introductions and begin their assault. Spider-Man finds a group of crates that protect him on three sides. He creates a web-shield with his new formula to protect him from the various projectiles.
Once safely inside his crate and web fort, Spider-Man begins to impersonate his enemies and use ventriloquism to make them angry with each other. With tempers already high, the criminals are easily manipulated into attacking each other. One by one they fall until only Boddy remains.
Boddy will not go down easily. He reminds Spider-Man that he's invisible and has the advantage [Of course, there's the matter of the floating gun. That's not invisible.] Spider-Man once again uses his ventriloquism to trick Boddy into revealing his location and captures him in a web-net. He webs up Vulture, Electro, and the Goblin and leave the four of them for the police.
This is as close as the series comes to having the Sinister Six. Three villains are drawn, and we have an invisible man leading them. Not exactly what Stan and Steve did, but there you have it. I'm sure that they stretched the budget to include this many villains at once.
I would have preferred that they bring in Dr. Octopus, Sandman, and Mysterio to make it as close to the true group as possible. All three of them have been introduced and defeated already. This could be done by reusing existing animation on new backgrounds. Since Kraven is not available, I would prefer Noah Boddy to the poor substitute hunter Harvey Clivingdon.
3 webs. Decent setup and very unusual final battle. It's not surprising that they had to cut corners at the end to have that many characters in one episode.