The Burning White Dragon

Draco Meteor/Dragon Pulse
Blue Flare
Focus Blast
Psychic

Nature: Modest/Timid
Item: Choice Specs

An all out Set. Draco Meteor for a heavy hit but possibly unreliable with choice specs in my opinion as constant use will make it weaker and weaker forcing you to switch out quite abit meanwhile Dragon Pulse maybe alot weaker but looks far more reliable with choice specs. Blue Flare gets STAB, focus Blast hit rock types and Psychic for coverage.

Physical Reshiram??

Its an option but not a good one. It can use Outrage and Stone Edge which are good but not any powerful Physical Fire moves, all it has is Flame Charge for a speed bonus which may help or Fire Fang with its flinch which with his base 90 Speed is possibly unlikely. In fact if you do decide to run with a physical one have both of them.

In double and Triple battles you can teach it Solar Beam instead of Psychic. I didnt put it into the 'The Burning White Dragon' set as it could hinder Reshiram outside of Sunny day possibly doing more harm to him, in which case a good partner would be either Groudon or a DW Ninetails thanks to their wonderful abillity to create permanate sunshine.