E.g. if Kyurem-B had Freeze Shock, and you then separates it to Kyurem and Zekrom, what would happen?
Here is how it works. If the Kyurem B/W knows Freeze Shock/Burn, then after it separates the Kyurem will know Glaciate. If it knows Fusion Flare/Bolt, after separation it will know Scary Face.
Source: Tested it myself