Hi, Metalwario, most of the God mode community nowadays remains in youtube, sharing videos of characters that demolish each others with one button press, you can find a lot of good balanced stuff by following places like the guild.
The vegeta undershirt is palette separation, in videogames a character has his original sprites and palettes that state what each colour will be in game.
This image is a good example of proper palette separation

You see that namor there? Depending on the separation on the original sprite, applied palettes can simulate other forms of clothing. You also noticed that vegeta has yellow hair on those frames with the blue sleeves, that is there so that his hair can be made black in the final version. You can only subtract detail with palettes, not add it, so the original frame must have as much information as possible.
In the same vein
if you have ken, you are limited to changing colours around those that are separated
if you wanted to give him different coloured pants in some palettes, you would have to manually edit every sprite to have different coloured pants, like this

and then in game to give him the all red costume, you would have the palette indicate what parts were red and what parts werent.
During game building you would never recolour manually a sprite, so an official game wont have like ten full spritesets with different colours inside, instead it will have one spriteset that is then mathematically recoloured using palettes.
I've tried to make it as simple as I could, but if you are still confused about it, I can try to give more examples, perhaps.
Oh, and vegeta has his arms separated so that later on, if they decide to, its easier to edit his armored costume.
