if("Saiyan")
mobcreation = new /mob/PC()
var/which_gene = pick("rage", "train", "legend", "god")
if(which_gene == "rage")
mobcreation.rage_chromosome = 1
if(which_gene == "train")
mobcreation.train_chromosome = 1
if(which_gene == "legend")
mobcreation.legend_chromosome = 1
if(which_gene == "god")
mobcreation.god_chromosome = 1
mobcreation.race = "Saiyan"
mobcreation.powerlevel = 200
mobcreation.powerlevel_max = 200
mobcreation.strength = 15
mobcreation.strength_max = 15
mobcreation.overlays += tail
mobcreation.Skin()
mobcreation.Hair()
mobcreation.Karma()
Does this do what you wanted? It should be easy to see how this code works.
Edit: yes, I could use switch, but everyone understands if, and not everyone understands switch or even "else if".
I can't help but feel like you picked a horrible source to learn from. You'd get a lot farther taking, say, one of Forum_Accounts' many frameworks and whipping that into a DBZ game if that is what you wish.