If you play a spider man with an effect like the amazing bag man, does it proc on all spiderman characters you have in play? or only on that specific character.

only that character

When a card uses its own name, it is referring to just itself; Bag-Man essentially says "Whenever this card becomes stunned..."

To refer to all characters named Spider-Man, it would actually have to use that type of wording---"Whenever a character named Spider-Man..."