Re: Thoughts of an Ikki Tousen RP
That's a tough one. The only guidelines I can think of, and they might not reflect the way things are in the anime/manga, are such:
Anyone with a magatama rank can defeat anyone without one with little difficulty. Thus a 100lb school girl could kick a 300+lb professional fighter. It may not be realistic, but these things are magic.
Toushi of the same rank should be roughly even in battle, but depending on style or circumstance, one would have an advantage. These sort of things would likly be decided mutally between the players if two PCs are fighting, not nessicarrily at the outset, but when it seems the momentum is shifting in one person's favor, it might be worth working together to make the scene memorable.
Against NPC enemies of the same rank, I guess similar guidelines would apply with both sides being roughly even at the start of the battle, but as the fight progresses, one will most likly gain the upper hand through creative fighting or other circumstances. Also, knowledge of your enemy's style would grant you a signifigant advantage in battles of the same rank.
In battles between Toushi of differing ranks of no more than one rank difference, the higher ranked fighter would obviously have signifigant advantages, with the weaker fighter only having a chance of victory with a combination of planning (knowing the enemy's style and weakpoints, fighting in a prepared area, etc.), cunning, and luck.
When two toushi of vastly differing ranks fight, the higher ranked one should be nearly unbeatable. We're talking a match-up like He Yi vs Lu Bu. There would be no contest. That said, situations may arise where a higher ranked fighter could be bested by lower ranked foes. Off the top of my head, some of these situations could include illness, poisoning, overwhelming numbers (even Lu Bu wouldn't be able to take on the whole Yellow Turban army), or betrayal (Dian Wei was killed during a suprise attack by someone who had surrendered to Cao Cao).
I think the best rule of thumb would be to make fights as fun as possible for both sides.
Oh, one more thing, two lower ranked toushi acting together might be considered on par with a single toushi of one rank higher?
Those are my thoughts.