Swords Dance Talonflame also makes a good partner for Mega Diancie, as he is able to remove steel-types such as Ferrothorn, Scizor, Mega Metagross, Jirachi, Scarf Magnezone, Skarmory and Grass-types such as the likes of Celebi, Amoonguss, Serperior, Mega Venusaur, and Mega Sceptile that pose a threat on Mega Diancie. Also great against Volcarona who otherwise kills Mega Diancie after a Quiver Dance.
In return, Mega Diancie kills non-Scarf Heatran and Tyranitar who would otherwise wall a Talonflame sweep. Of course, this stacks Water-type weaknesses, so partners like Serperior, Manaphy or NastyPass Celebi, who can dispose Water-types are appreciated. Rotom-W is also an option to cripple offensive Water-types and at the same walling bulky Water-types, while being able to kill Scarf Heatran and being a more stable counter to Birdspam.