If Darkrai attacks with "Abyssal Sleep", can Pokemon Ranger clear the effect of flipping 2 coins when Asleep?
Asleep, Poisoned, etc. are Special Conditions, regardless of how many coins you need to flip or how much damage the poison condition does. Therefore they are not altered by Pokemon Ranger.
Source: TPCi Rules Team (2016-11-10), TPCi Rules Team (2016-12-08)

Relevant cards

Note: All applicable cards may not be listed below.
XY11_104
XY11_113
SM5_77
XYP_XY194
XYP_XY194