The only on there that isn't possible is using Riivolution. There's a Riivolution xml for BrawlEx, but it's pointless.

The difficult part of the rest of it is, if I understand correctly, the custom CSS.

You don't need to edit the bx_fighter.rel. Just put it in the module folder.

Take everything inside the ALL CHARS folder. Put that in the root of your SD card that's 2 GB or less. Load Gecko and launch Brawl.

Just add this and you can use larger sd cards.

If you use the SDHC code and a launcher other than Gecko, you can use a SD card that's as big as you want.

Are you adding or replacing pictures?

Put what? My BrawlEX? I followed that tutorial on the main post to a T.

Do you have the Custom CSS Code and CSSRoster.dat?

Do you have the .pac and .pcs files?

When you import textures, use CMPR. Try lowering the vertex count, however you do that.

Here you go.

Open up the CSSSlot. Look for the last 0C. Change that bit to anything above 03. For example, lets use Peach. The bit after 03 would be 06, since here normal highest is 05. Then you use the second bit for the character file. It would be FitPeach06.pac/pcs. Keep doing that until you reach the number in the fighter config. The bit after your last costume has to be 0C. I'm not sure how G&W works.

Download this and place the files appropriately. Also remember to replace your file patch code with the new one. Use this tutorial.

As far as I know, you can only give individual characters more costumes (or less) is by using BrawlEx files.

If you haven't added In-Game Cosmetics.. add them, that's why its freezing.

That isn't true. If you use a character's cosmetics that already exists, it will be fine.

Open you fighter.dat in the config utility and make sure you have all the files it says.

Does it happen with a specific character?