What are Career Tributes and how are they threat?

Answer 1

Career tributes are tributes from Districts 1 and 2 (and 4 in the book, but not in the movie)

They have trained for the games their whole lives, even though it is illegal, however they are favoured by the Capitol and so are not punished. The fact they have trained gives them the upper hand and so they usually win. They wait until they are 17 or 18 and then volunteer at the Reapings as they have a very high chance of winning the games.

They are a threat to the other, less well-off tributes as they have skills that they have perfected over many years.

Answer 2

The career tributes, held to be I believe District's 1,2 and 4, are a definite threat in the Games. While it is strictly against Hunger Games rules to train before the Games, it goes on relatively unnoticed specifically in these Districts. This puts all the other tributes at a disadvantage because of the additional training these tributes had.