So I've been DMing for a while but it's mostly just been premade modules and stuff like that. I decided that I wanted to try my hand at writing a small supplement and adventure that I could run or other people could run as well. I got into the Kaiju Paradise fandom and been having a great time with it and I've been struck with some inspiration. A huge part of the game is all the different species or Raytraxes about 2 dozen, although I admit that doing all of them might be a bit much for a first time. (See here for the line up: here if you're interested). Since they're such a huge part of the game and I personally find character creation to be one of the most fun parts, I wanted to start with writing race options.
I want advice on how I make the character options feel both feel thematically different and that they play mechanically different. How I can make the Raytraxes each unique and interesting in their own ways while avoiding having to reuse abilities?
I would also like to ask if there are any suggestions for websites I should use for this. I'd prefer something that helps keep the individual sections organized but that can still be ported over to or used without a paywall.
If anyone replies to this, thank you very much .