Hey Charizard ! Your post belongs to Pokemon essentials forum, not ressources ^^
But still, let's see your problem. What do you mean about adding ability messages?
If it's about the ability description, you'll have to go in Yourgamefolder/PBS and check abilities.txt, then add your ability message here by copy/paste an already existing line (Please keep in mind to change the number of the line since it will conflict)
If it's about adding messages that display during the battle like (Miltank was poisoned by Magikarp's poison point) then you have to code your ability to make it display a message using :
@battle.pbDisplay(_INTL("YOUR TEXTMESSAGE"))
You can modify this to put a variable {1} and a variable {2} when 1 would be the pokemon's name, and 2 the ability name for example, but I don't have the whole process since I'm a noob :3
If it's anything else, please ask ^^