While it is not the best pin trading park, it has the best pin trading board you will find at any Disney World park and we are talking specifically about Hollywood Studios.
If you are looking specifically to make pin trading a part of your day, Hollywood Studios is the only park that offers pins without actually buying a trip to the park. Imagine that.
Once you clear security, if you don't want to go into the park but did feel the need to ride the gondolas from one of the hotel resorts or Epcot, you can look at the first pin board before you enter the park. Simply walk over to the left side of the entry gate and ask the cast member at the small gift counter to see their board.
The board is a decent size and is typically filled with pins. Obviously you are not going to visit Hollywood Studios simply to get pins but if you did ride the Gondola for fun, why not walk over and take a look before you get back on and head back to where you came from.
If you are entering the park, the best board at any park is located immediately to the left of your entry next to guest services. You walk up the front steps and go to the back right. You can't miss this massive trading pin board and chances are you will encounter plenty of other guests that are skimming over it.
In the window in front of the board, you may encounter those that I call "The Professionals". I have seen them more than once and they simply sit in the window with bookd and books filled with hard to get pins and they will wait for you to make a trade at the board and then see what you traded. Why? Because every now and then, someone trades a value pin and they pounce on it.
Another spot at park entry is in the middle kiosk as soon as you enter. While they do not always have a board, it is worth checking.
After you leave the front of the park you will find pinboards on Sunset Blvd. that ends at Tower of Terror and Rockin' Rollercoaster. The board is located at a pin shop located between two beverage and food stands. It's a small kiosk and easy to miss.
On the other side of the park you will find pinboards next to the Frozen: First Time in Forever Sing-a-Long at the counter of a small gift stand before you get to the Olaf meet and greet.
The next one will be found at the Backlot Express food service counter. You need to ask one of the cast members at the counter to see the board which can be a bit taxing if the restaraunt is busy. They don't open until 11:00 am which can be problematic as well. The board is larger than the normal ones but not as big as the main board at the entrance.