It should always be done for fun and if someone is offering you money or other compensation for it even better but the leagues are almost always going to feel unfair if separated by cooling methods. If someone is on air and can't afford a high end water cooling setup or they live in Australia where is is 40c out when it is - 5c for me that is a huge difference between the two even though it is both ambient cooling. If someone in Australia is using a fishtank chiller they are going to feel like it is unfair that even if it is the same temperature as it is for me during the winter that they are put against people using dice. In the extreme league I am put against people using liquid nitrogen which is 90c colder than my cascade. My solution is to bench devil's and 775 because its cold bug is usually very close to that of my cascade. If you are on water look at the database and find something worth points using water or air. Hd 4350 the top scores are all on ambient cooling and is worth over 30 points. Or 2500k, 2600k, 2700k are worth lots of points and have a high cold bug. It is about what you are willing to learn for points and if you want to get points put in the work if not then just do it for fun and don't worry about the leagues.