This wikiHow teaches you how to randomize a Pokemon ROM on your Windows- or Mac-based. You'll use the Universal Randomizer program for any Pokemon game.

GAME INFORMATION
Game Name	Pokemon Emerald Randomizer (Hack)
Region	USA
Console	GameBoy Advance
Game Release	2005-01-05
Genre	Hack, RPG
Publisher	Game Freak
Languages	English
Image Format	.gba
Downloads	153,779
Users Score	Rating: / 5. Votes: No votes so far

Description:

1. Pokemon universal randomizer How to use Pokemon Randomizer? Apply the following steps to take advantage of a universal randomizer. Firstly, you should press open to explore the randomizer. Then select those aspects or services which you would like to have in your Pokemon game. After it, just press randomizer (save) and ROM (save), to save changes.
2. Pokemon xy Randomizer Nuzlocke, sonic and knuckles prototype, pikmin 2, crysalis, totally spies 2, game gear, sonic advance 2, Caslevania 1, super kaizo amrio, emuparadise, mga man x, no 8120 2nd: 12,225.

Create your own personalized Pokemon Emerald Randomized ROM:

Features v. 2.2:

• Specify or set random starter Pokemon
• Randomize Wild Pokemon
• Randomize Unique Pokemon
• Choose or randomize starter Held Item
• Switch Pokemon Stats Around
• Randomize Pokemon Types
• Randomize Pokemon abilities
• Randomize Wild Held Items
• Palette: Use Type-based or random colors
• Redefine trade evolutions
• Randomize pickup Items
• Randomize Field Items
• Randomize Trainer Class Names, Held Items, Use Items.
• And More...

Usage:

1. Download the randomizer and the rom
2. Open Randomizer (Requires Java installed)
   
3. Extract The Emerald ROM with winzip/rar/7-zip and open it with the randomizer (Ignore CRC error).
4. Choose your perfect randomized settings.
5. Save the new randomized ROM.
6. Play it!

Credits: http://artemis251.fobby.net/downloads/emerald/

Alternative 2: Universal Pokemon Randomizer

Use the Universal Pokemon Randomizer v1.72. The Process is same as above.

Credits: https://pokehacks.dabomstew.com/randomizer/

Screenshots:

Pokemon Emerald Randomizer (Hack) GBA ROM Download:

Universal Pokemon Game Randomizer Roms

Universal Pokemon Game Randomizer Tutorial