Teams are like tables in that the number of people on them is limited. If you're holding a golfing event, for example, you might only want 4 people on a team because that's all that will fit in a golf cart. For teams like this, you want to use Tables/Teams, not Groups.
However, if your event or organization naturally creates group of an undefined size, Top Teams can be lots of fun. This makes the most sense when groups can win a prize.
You create/add all of the groups in the dashboard which gives your fundraisers a chance to join them when they purchase tickets.
Examples of using Top Teams:
Bar Foundations—Lawyer Sections compete to win a Happy Hour event hosted by the organization
Cooking Competition Events—Already divided into teams, groups vie to win the cooking contest AND the fundraising competition.
College/University Greek Chapters—Compete to raise the most money
Honorees—Guests rally around honorees and raise money in their honor