The term "extreme" refers to a comprehensive randomization of game data to create a state of total unpredictability. Key features often found in these versions include:
A Fire-type Blaziken might become a Water/Electric type with the Wonder Guard ability. Pokemon Emerald Extreme Randomizer Rom -NEW
Evolution chains are decoupled from their original designs. A small Caterpie could evolve directly into a legendary Rayquaza. The term "extreme" refers to a comprehensive randomization