marvel has the characters ride in on atv and do a photo session and greet period over by spidey daily.
during special events you will see parades. think mardi gras.
you need to check the park map guide when you enter the park to see what events will be held and the times.
you will find characters that way.
universal has a different way of displaying their characters than other parks.
i think you can compare disney and six flags more closely for the way they do the parades, fireworks and characters. they are pretty much similar in that way.