Dragon Dance would make a physical set more viable but makes no sense in terms of flavor(although neither does Totodile and co getting DD :p) With DD, mixed Magmortar would be a huge issue to deal with. Mons that outspeed and OHKO like aerodactyl will become more popular, as will mons that can wall Magmortar(like Flash Fire Entei when released). Rapidash might become more popular: it has flash fire to threaten a sweep and can outspeed and beat Magmortar with HP Rock. OK, this is a BIG topic: What if, just like Life Orb, GameFreak released: a) A Speed Orb, which boosts speed by 30% but gives 10% recoil each time the mon attacks in similar fashion to life Orb and b) Defensive Orb that boosts both defenses by 30% each but has 10% recoil each time the mon attacks(would be pointless if the recoil were to happen when hit because the recoil would offset the reduced damage from the attack making the item pointless) This would revolutionize the metagame. Speaking strictly of RU, Scarfers would start using a Speed Orb instead because nobody likes being locked. With the proliferation of the Speed Orb, naturally fast mons would see a decline in usage because most mons would then be able to just run a speed orb and outspeed. Defensive Orbs on the other hand would help stall teams greatly. Strategies like Stall would be more rampant, and mons with behemoth defenses like Regirock and Alomomola would be more popular. On the other hand, sweepers that can forego the extra power will use these items so that after revenge killing one mon, they can tank a hit and get another kill.