This is a tutorial thread for editing graphics in Pokémon GBA games. If you would like anything added or if you need help please post it in this thread or pm me. 
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Table of Contents: To jump to a section press ctr-f an type in where you want to go to.
A. Title Screen [AT]
B. Intro Screen [BI]
C. Pokémon [CP]
D. Items [DI]  
E Tile [ET]
F. Trainers [FT]
G. Overworld Sprites [GO] 

For graphic hacks it's best to use Fire Red, Emerald, or Ruby. Some tools don't work on Leaf Green or Sapphire. If you must use a Leaf Green, Ruby, or Sapphire then you'll have to find out how somewhere else. If someone wants to write their own tutorial on this then you can pm me in and i'll add it to this thread. (it will say it was contributed by you) 


A. Title Screen [AT]
Now for this you will need to play close attention. If you mess us one thing the whole title screen could get messed up. This part will be broken up into three parts. Changing the title Pokemon, changing the background, and changing the logo. Before we start you'll need to download Irfan View, APE, NTME, GIMP (or photoshop) and unLZ-GBA. 

I'll start by explaining how to edit the title pokemon. First download a picture of the pokmon that  you want to use. (it doesn't have to be a pokemon just a picture that is 64 by 64, 80 by 80, or something that is a multiple of 8) I like to use http://pokemondb.net 
Now open it up in Irfan View and open  the picture you want to use. Then go to image, edit pallet. If the option isn't available option you'll need to find a different picture. I'm not really sure why it does this sometimes. Now after you click edit pallet it should look like this: 
http://s23.postimg.org/xinhkdpdn/Colors.png
Now double click the background color and change it to the fourth color. (the bright green) 
http://s9.postimg.org/ldc5wakwf/Green.png 
Now save the picture as a .png file and export the pallet. (image, pallet, export pallet) You have just indexed your first image . 

Now open up NTME and the .png file from before. Where it says "Tile Selection" keep adding to the width and height until until a red box covers the whole image in the top left corner. Then in the bottom right corner where it says "Preset Sizes" click on "FR/LG TS" (or whichever game you are using) Next on the bottom next to pallet map click on the letter "D" (its small so you'll have to look close) Now where it says "TileMap" click anywhere you want to paste the picture. Then save the tile map, but don't close NTME. 

Open up unLZ-GBA and your rom now. In the box to the left of where it says "Goto" type in 2011. This is the offset for the Charizard in Fire Red. I'll get the numbers for the other games soon. The picture should look like a Charizard, but it's pixels are rearranged. If it doesn't look like the Charizard then you should look around the offset I gave you. It should be somewhere around there. First import the .png that you want to use, click write to rom, copy the pallet offset, and press ok. If it gives you an error then you might of done something wrong. Make sure you use the correct sizes. Then click next, then file, load raw, and load the raw you just made. Now go into Visual Boy Advance or your emulator and test it out. 

Your image on the title screen probably looks messed up and it might not be where you want it to be. If you want the picture to be in another spot you'll have to go back to NTME (remember I told you not to close it) and move it. Then go back into unLZ-GBA and add the new raw. The picture looks messed up because we didn't edit the pallet yet. Open up APE and load the rom.  Where it says "Pallet Loading Options" make sure Load from offset is checked, then paste the pallet offset that you copied earlier, and click load. Now in the bottom right corner there should be a pallet with a blue arrow. Click that, then change the file type from "APE Pallet" to "PaintShop Pallet" and load the pallet from Irfan View that you took earlier. An error message should pop up now. This is normal. Click ok and do the same thing again. Now it should give you another error. Now you'll need to take a screenshot of APE. (don't click ok yet)
http://s10.postimg.org/5qkpwwqmh/APE.png 
After you've taken the screenshot open the screenshot in  paint or another program and click ok in APE. Now APE will close. The open APE back up and load the pallet offset again. Make sure you can see the screenshot that you took and APE. Change the numbers in the "Changed Pallet" to the numbers in the screenshot. 
http://s24.postimg.org/7xfuykwsl/APE_2.png 
Now click replace, then load, and test is out . 


Next I'm going to explain how to change the pokemon logo and where it says fire red version. First open up visual boy advance, go to the title screen, click on tools, pallet viewer, save BG, and save it as a .act file. Now you'll have to open up unLZ-GBA and go to 2009 for Fire Red. Change everything so it looks like this:
http://s11.postimg.org/qcll6o8f7/Title_Screen.png 
Then save the picture as a .png. Now open up GIMP. Open up the title screen picture and change the color table to the .act you just saved. Bellow where it says "Pokemon" the top of where it says Fire Red might show up. Erase this. Now where it says "Fire Red Version" Replace that with whatever you want it to say. You can also change "Pokemon" to whatever you want. Now change the pallet to grayscale and save the picture. Now back in unLZ-GBA import the new picture. If your image is too big then you'll have to use free space finder and change the image offset. (this is called repointing) Now test it out in VBA. If you don't like the colors then go back in GIMP and change it. 

B. Intro Screen [BI]


C. Pokémon [CP]
You can use nameless sprite editor to edit this. It can edit Pokémon, footprints, and event the Pokémon icons.  You can even export these things and edit them in paint or another program then import the sprites. These options work in all Pokémon games. 

D. Items [DI] 
You'll need Item Image Editor for this. It doesn't let you actually edit the sprites, but it gives you the offsets of the pallets and the actual item sprites. You can use APE (advance pallet editor) to edit the pallets. Just copy and paste the offset in and then edit it. And you can use unLZ.GBA to edit the sprites. Just look for the sprites (it should be around the offset in Item Image Editor), save it, edit it, them import the new sprite. 

E Tiles [ET]


F. Trainers [FT]
This part is for Fire Red, Ruby, and Emerald. You'll need nameless sprite editor 2.1. if you read the pokemon section you should know how to do this. 
For Emerald you'll have to use unLZ-GBA. Look around sprite 1939 and pallet 1109.
http://s17.postimg.org/rx7qfeexb/Pokemon_Emerald.png 
I can't help you on inserting sprites, sorry. For Leaf Green or Sapphire you'll have to find out how somewhere else. Maybe look in unLZ-GBA. 

G. Overworld Sprites [GO] 
To edit over world sprites then you should use either "Nameless Sprite Editor 1.75" or "Overworld Editor" download links for both of these are in the toolbox section of the thread linked above. These are very simple programs. You just open it and then edit. I don't really need to explain anything else.