There are small things it does to give you a better experience. For example, a trainer's random Pokemon will not suddenly use moves they were predefined to use in the original game - they will fully obey the (randomized or not) movesets they have been provided with. A decent amount of attention to detail has been invested in this randomizer and so pesky parts of the original games are unlikely to show through. By sending a couple of pieces of text or a small file you can easily make sure everyone has the exact same game to play with, without having to send around the entire ROM every time. An important part of Pokemon is competition, and racing your friends to complete a particular random Pokemon game can be a great experience. You can easily create the same random game repeatedly. Every main series Pokemon game released in the US is supported, from Red to Black2 and everything in between. If randomizing things like Pokemon types is just too confusing or unenjoyable, the randomization can be easily tailored to your particular needs.

Naturally, you are able to choose exactly what is randomized in your particular ROM.

The moves taught by move tutors, for games within which they are significant enough.

The names of trainers & the classes they belong in.

The 'static' Pokemon which you either are given, fight on the overworld, or are sold.

The ability of each Pokemon to learn each TM or HM move.

The contents of each TM which can be taught to Pokemon to give them additional moves (HM moves are not changed to make sure you can still beat the game).

The moves that Pokemon learn by gaining levels.

The abilities of each Pokemon, in games where they exist.

The base stats which define the potential of each Pokemon.

The Pokemon that Trainers use against you.

The Wild Pokemon you encounter in grass, caves and other places.

In the same vein as previously released randomizers, it provides a customized gameplay experience by allowing you to randomize many things: The Universal Pokemon Randomizer is a program which will give you a new experience playing Pokemon games.

Heartgold randomizer