How do I make a battle start after talking to an NPC?
I'll assume you know how to make enemies. (if you don't, read the HOWTO)
Make a battle formation that includes the enemy(s) you want to fight. It does not matter if you add this formation to a formation set. Formation sets only matter for random battles. Remember the number of the enemy formation. You will need it later.
Back up to the main menu, and go into the Dialogue editor. Create a text box that says "Graaah! I am a monster!" or whatever. Pick Edit Conditionals. Find the line that says:
never do the following
fight enemy formation 0
and use the left and right arrow keys to change it to:
always do the following
fight enemy formation ?
where the ? is the number of the enemy formation you want to fight.
Then, attach the text box to an NPC. When you talk to the NPC, the text box will be displayed: "Graaah! I am a monster!", and then you will fight the enemy formation. Usually, you will want to make the NPC one-time-usable, so it will disapear after the battle. Also, remember that running away from the battle would be the same as winning it, so If this is a Boss, you should edit the enemy bitsets for at least one of the enemys in the formation and turn on the unescapable bitset.