USA Pickleball is the standard for the rules of the game. They can be found HERE

You may be aware of a few diffrent rating systems currenly out there. USA Pickleball (UTR-P) is the required rating for sanctioned tournaments. There is also DUPR, which is “dubbed” the most accuate rating, which is based on a special algorithm, including matches played against opponents of various tournaments to include both Sanctioned or Unsanctioned Tournaments

Skill assesments can be found under USA Pickleball to give you an Idea of the required skills needed to possess a certain skill level. IPTPA also offers their own skill assessment. It is important to understand the subjectiveness to each individual as consistency is the KEY to each level