WEPF World Eightball Pool Rules - Played with 2” red/yellow balls. WPA Blackball Rules - Played with 2” red/yellow balls. There are three sets of rules for 8 Ball Pool which are most commonly played: This page will clarify the various different pool rules and prevent confusion. When playing informally - for example, with friends - this can lead to disagreements over the correct ruling in a given situation. The rules for 8 Ball Pool can be confusing, as there are several international variations.