Gagagigo the Risen the second non effect Xyz monster as you may noticed it doesn't have any text beside the requirement of summoning making it very simple but in other hand regading attack and defense it is very good with right cards you may deal huge damage for the opponent 

The summoning of it can be performed through Ultimate Offering combined with Gadget guys taking the advantge of Gadget effect by adding each other to hand  when they get summoned to field so activate Ultimate Offering  followed by summonig  three copy of Green Gadget, Red Gadget, and Yellow Gadget at once to overly them and  bring Gagagigo the Risen to action of course there is no use of its material Oni-Gami Combo comes in handy there to cause more damage for the opposing.