(including the normal type)
They don't have any. The real trio do not have any signature moves, but Regigigas gets Crush Grip, a move that none other can learn, rendering it it's signature move.
Source: http://bulbapedia.bulbagarden.net/wiki/Crush_Grip
Regirock, Regice and Registeel doesn't have any signature moves, but Regigigas can learn Crush Grip which has a power of 20-120 depending on it's current HP compared to it's full HP, the higher, the better.
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