I guess this will be my first question on this forum.
So, i haven't figured out yet how to make a "Boss Battle".

You know, like after talking to an NPC, then the NPC will like say "Lets battle", then a boss battle will occur right after the message box disappears, with the escape command disabled.

This is actually pretty simple to do.

First, make an event with the NPC dialouge. Then, after the dialogue (in the same event) add the event command Battle Processing. You'll see a box that let's you choose which enemy troop the battle will be with, and whether the player can escape or not.

To add more feeling to it, you can use the Change Battle BGM command before the Battle Processing one to set some special boss fight music, and then after the Battle Processing command, use the same BGM one to change it back to normal ready for normal battles. I hope that helps, but if I didn't explain it well, let me know.

Thanks, i must have missed that "Battle Processing" button, as i was looking for an event button that allows battles in events.
Thanks EvenAngels.