AN ARTICLE ON BATTLE BASICS?

There are many ways to get battles right, so an article like that would most likely be "how to make battles my way" rather than getting it right. So, all I can do is to give you some tips that I think is a good idea.

Don't give STR, DEX, AGI and INT low values, RMXP does bad things if you do so. Keep them above 20 for all characters even at level 1.

Don't make ATK, P-DEF and M-DEF progress to quickly. In many RPGs, characters will at the end have maybe 20 times the attack power they had at start. This will not work well on XP. If ATK progresses quickly, spells will very frequently have to be replaced by stronger versions. I suggest that at end game, the characters have an ATK score about two or two and a half times what they had from the start. Remember that the STR score also determines how much damage an attack does, so a character can still deal far more than twice the damage even if ATK is only twice as high. P-DEF and M-DEF should increase as quickly as ATK does.

Choose the battle length carefully. If battles are to short, any form of defensive skill will become useless. The reason for that is because while defensive skills reduces the amount of damage you take, so does killing the enemies. Now, if it takes say three attacks to kill an enemy, you need three actions to decrease the amount of damage you take by simple killing an enemy while a defense up spell will give you that benefit at the cost of only one action. However, with short battles, enemies will die quickly meaning you get the defensive benefit from offense really quickly, thereby obsoleting the use for defense.

On the other hand, if battles are to long, you will bore the player. As a rule, once the player kills even a single enemy and has all characters standing and none of them near death, the battle is practically won. The rest is just cleanup. You don't want that to take to long. I suggest about four rounds of combat for the average random encounter. Most RPGs have shorter battles than that, so make the random encounter rate a bit lower than usual to compensate.

Characters need to be able to do more than one thing, but should not be able to do everything. If the characters are only good at one thing, it becomes obvious what they should do. Nobody will ask "should I have my healer heal and the fighter attack or should I instead have my fighter use a potion and let the healer attack with her wet noodle rod?" However, having to many characters being able to do the same thing can also trivialize decision making. For example, with three character being able to heal, the player will never have to decide whether to heal the healer or to heal the most wounded character first since there's two reserves if the healer croaks. Generally, you want the characters to be flexible, but still have a lot of unique skills.

There's not much more I can tell without first knowing what you're going for. Some games limits the amount of healing the player has access to while other games gives the player practically unlimited healing. Some games let the player assemble a party while other games has a set party. What works and what doesn't work depends on a lot of factors.