[Scripting Question] Shadow Pokemon Help and Discussion

Hello everyone, I just started my first pokemon fangame and was wondering if anyone would be interested in discussing with me. First I'm trying to figure out how I can add the Shadow typing to my pokemon. For example the Electric Mouse Pokemon Pikachu would turn into a Electric, Shadow typing. While a pokemon with a dual typing such as Bulbasaur would turn into a Grass, Shadow type. (I already edited the types.txt file and added the Shadow typing. Just looking to add that typing onto the actual pokemon.) If anyone could give me some assistance it would be most appreciated. Secondly I'm looking for some input on how to make Shadow Pokemon more balanced. Since Shadow Pokemon aren't able to level up it puts them at a massive disadvantage until they're purified. I need some ideas to make Shadow Pokemon more balanced making it more of an alternative compared to their regular form. Hope to hear back from you guys

You'll have to edit some images in Essentials (what I presume you are using) And add an additional type box to battleFightbuttons.png, pokedexTypes.png, types.png, that are located in the Graphics folder inside pictures. In your script editor, locate EliteBattleUI and add your custom Type in... types, (forgot line number, might check later.) You can change a Pokemon's type in Pokemon.txt file and moves in moves.txt too.

At first I was confused about Shadow Typing because what even is that. But I'm guessing this is from Pokemon Go? Not sure how to balance it out though, maybe you could make their attacks stronger than normal?

Shadow Pokemon originally appeared in Pokemon Colosseum and XD Gale of Darkness. They are basically more aggressive versions of pokemon where they ignore and attack their trainer. One quirk is that unless you purify them they are unable to gain any exp after battle. Another thing is that Shadow Pokemon don't change their typings while Shadow. While Shadow pokemon have exclusive shadow type moves only they can learn, their typing isn't altered to match.