Criteria to play for NBA all star game?

The starting lineup for each squad is selected by a fan ballot, while the reserves are chosen by a vote among the head coaches from each squad's respective conference. Coaches are not allowed to vote for their own players.

The head coach of the team with the best record in each conference is chosen to lead their respective conference in the All-Star Game, with a prohibition against repeat appearances.

Fans vote on the starters for the game, selecting three frontcourt players and two guards from each conference. NBA coaches vote for the reserves for their respective conferences, none of which can be players on their own team. Each coach selects two guards, three frontcourt players and two wild cards, with each selected player ranked in order of preference within each category. If a multi-position player is to be selected, coaches are encouraged to vote for the player at the position that is "most advantageous for the All-Star team", regardless of where the player is listed on the All-Star ballot or the position he is listed in box scores.

If a player is unavailable for the game due to injury, the NBA commissioner selects a replacement for the roster. If the replacement is for a fan-selected starter, the all-star coach chooses the replacement in the starting lineup, and is not limited to the commissioner's addition to the roster.

It is possible for more than one All-Star to be selected from one team, but there has never been more than 4 All-Stars represent a team in the game.

For the Slam Dunk contest, players nominate themselves as competitors. Usually it is up-and-coming youngsters who take part in the challenge, though there are no rules(that I am aware of) stopping more experienced players participating.

For the 3-point contest as well, players nominate themselves.