Attacks » Damage Transport
Can I choose to move less than 4 damage counters on one or more of my Pokemon when using Drifblim's "Damage Transport" Attack? Or can I choose to skip any of my Pokemon?
No, if you have 4 or fewer damage counters on any of your Pokemon you must move them.
Source: Ultra Prism FAQ (2018-01-19), TPCi Rules Team (2018-02-01)
Attacks » Damage Transport
What happens during Drifblim's "Damage Transport" Attack if I have less than 4 damage counters on one or more of my Pokemon?
If there are 4 or less damage counters on one of your Pokemon you must move all of them.
Source: Ultra Prism FAQ (2018-01-19), TPCi Rules Team (2018-02-01)