There are 3 default actions you can make your creature take on the action window (Alt + T) and one extra. Creature Attack - Creature attacks target by itself. Press 'Alt + Click Target'. Follow - You can leave your creature at one spot and not follow you. You must reactivate it to make it follow you again. Press 'ESC x 3'.
Joint Attack: Creature and Characters attacks the target at the same time. Depending on the movement speed, one may start attacking over the other. The monster will first counterattack whoever attacked first, but will eventually attack whoever deals more damage. Press 'Ctrl + Click Target'. Move: Now this is not on the action window, but you can make your pet go anywhere by performing Shift + Click on any spot on the ground.
As the creature fights alongside you, it will also gain experience and JP. Yes, the creatures can use rappelz-item.com/tag/skill/">skills too! Their stats are permanently fixed however.
It will gain approximately 10% of what you earn when it is summoned, and it will gain only 1% when it is not summone.