Anything Goes Pitching
The Anything Goes style of pitching is just that, anything goes. Any pitch style may be used with any count and with any batter. It is up to the batter to determine whether to swing at the pitch or not. This type of game is typically low-scoring. Most purists consider anything goes the only proper way to play RBI, and most of the RBI Tournaments are played with anything goes rules.
One variant of the Anything Goes style is that some people play with only one starting pitcher per game. Both are technically anything goes styles however.