Create more than 1 advanced topic types I have a content type called advanced forum topic, which is created from the Advanced Forum module.

I would like to have 3 different kinds of topics(General, Player, Team).
Each of this has different fields. My thought was to organize these into Field collections. Is there a way that I can choose the topic type with a dropdown menu and then the rest of the fields in the collection would pop up dynamically?
You can easily do your requirement with Conditional Fields module. You can show different fields depend on the select list of topics.

Conditional Fields allows you to manage sets of dependencies between
fields. When a field is “dependent”, it will only be available for
editing and displayed if the state of the “dependee” field matches the
right condition.
When editing a node (or any other entity type that
supports fields, like users and categories), the dependent fields are
dynamically modified with the States API.