Creating summons that stay in battle? I suppose you'd have to:

1) Create that summoned monster's charset/battle charset and add that as a new character in the Hero tab.

2) Have the "summon" skill set a switch. Add this skill at whatever time the character learns it.

3) That switch should activate a common event that adds that summoning character to your party, which has a built in "dismiss" skill..

4) ..which calls a common event (through a switch) that deletes that character.

You'll probably also want to add an auto-start event on every map that does #4 in case that summon stays until the end of the battle.

This technique allows that summon to gain levels as well - make sure to set the experience / stat curves appropriately. It also keeps everyone else in the battle there - if you want, make the common events add / subtract everyone else.

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Running up and hitting someone? That's easy, but you have to do it on a per-item basis. Just go into the Items section of the Database and click on the weapon. You'll see the Animation box - click on the Set button below it. Another screen will pop up. Find the "Movement before attack" drop-down box... you can figure out what to do from there.