Skill commands.

Okay I've not yet seen on here where this may or may not have been resolved for anyone so I'll just ask it here until otherwise made aware of any thread answering my questions.

Firstly: So I have decided to start getting serious about making a little rpg for my own amusement, as well as for friends and such to play, (nothing publicly playable in other words) but while looking through how I wanted it set up I've found myself in a bit of a tight spot.

{Background info on how I setup characters. Skip this section if not interested in knowing about them.}
I created 10 characters based on myself and 9 other friends. Each one I designed with the intent of allowing them use of a single type of weapon and specific elements out of the categories of Earth Fire Ice Lightning Water Wind Holy and Shadow. (Granting more to certain ones and less to others based purely on what I see most befitting to them.) As such everyone has the common battle commands of Attack, Magic, Item, Defend and Escape. They also however have the Skill command which is where I planned to implement their own special or unique sets of skills that only one person (or possibly a select few characters) can learn and use. And so begins my challenge...

Issue at hand:
As mentioned in the background info I want them to have skills that are fairly exclusive to them as well as not a form of spell technically. Things such as commands that do healing and status removals or inflictions are one thing and simple enough to do for me but it's commands that act in a manner of Steal to take items or currency from an enemy, doing a move that is supposed to do a 12 hit combo attack using the person's weapon, or things like "Character sacrifices 10% of their max hp to divide that hp into hp healed amongst the other party members", and moves where "Character sacrifices X% of max hp to deal X damage divided amongst the enemies". Other moves I'd like to try creating would be ones where they're only accessible if certain conditions apply (i.e. like how in FF8, with the exception of Aura being used, characters had to be in critical HP to use limits)

Update of questions:
I'm also looking to find a way for making characters able to Counter Attack and a way to make a skill like the Cover command from FF games.

If there's anyone able to help me in figuring out how to make this kind of stuff realized in RM2K3 I'd be most grateful.

Thanks in advance to all suggestions and advice.