It doesn't tell me anything about why MP/TP is important and why it's important to guard or anything like that,
I think you misunderstand the purpose and flexibility of the engine.
YOU, as the developer, decide what and how important what is in the game.
For example, why do you think MP and TP are important?
There are some games where they are, simply because the developer made the enemies in a way that they can't be defeated without the use of skills costing some of very limited number of MP or TP.
And then there are games that don't even have MP and TP, because all skills can be used with zero cost - or where the cost of two or three MP is neglectable because the actors have several hundred MP at the beginning.
Same goes for the damage formulae - YOU decide what the damage is based upon. The default formula of 4*ATK - 2*DEF can be edited by the developer.
And none of that even considers that there are dozens of battlescripts that change how the battlemechanics operate...
Because of that, you cannot make a general battle tutorial - you have to select a game project, then you can make a tutorial how that specific game handles battles.
And most of what you'll write in that tutorial will be useless in most of the other games developed with RM.
And by the way - elements are nothing but placeholders for damage rates that are completely independent of each other, you as a developer set if something takes more damage from a certain element or not.
If you decide that an ice elemental takes more damage when attacked by ice attacks and less when attacked with fire, that is equally possible like a project where an ice elemental is immune to ice damage and takes double damage from fire.
NOTHING is fixed - you as the developer decides how to handle what.