We recommend selecting one variation to run a launch for when you have a listing with multiple variations. Using multiple variations with a launch can dilute the ranking benefits. Additionally, if your coupons are applicable to each variation there is the possibility that a buyer will use a single code to purchase each variation at a discount.
The best way to go about this is to ensure that the URL and ASIN link to the specific variation you intend to launch. You will also want to clarify which variation the coupons apply to through the title that you create for your product on the Viral Launch Launchpad. (i.e. 'Small Black Slippers' or '30ct multivitamin')
When setting your max order quantity in seller central be sure to apply the setting to the ASIN that you're using for the launch.
Not sure which variation you should launch? Ask us at launches@viral-launch.com!