And to complete the regi family we come to Regigigas. Yes this may be a little OP so get ready.

Regigigas gets the Sheer Force ability when it Mega Evolves, improving the power of its moves with secondary effects but taking those effects away. This includes moves it gets like Zen headbutt, fire punch, iron head and rock slide. It gets a HUGE boost to its attack and a slight boost to its defenses and a slight drop in its speed. It now has more armor and is bigger and hold a huge War Hammer that is taller then Regigigas that can shatter entire continents.
Stat boosts:
100 attack
10 defense
10 sp defense
-20 speed