A1 : Key Darkness-type cards include Scolipede, Weezing, Umbreon, Darkrai ex, Nihilego, Alolan Muk ex, Guzzlord ex, Arbok, Muk, Koga, Sabrina, Professor's Research, X Speed, and Pok Ball
it seems thats more relevant than ever these days
If it does trigger, the ability will check again as it tries to resolve
Another good aspect of the Skeledirge card is that it is a regular Pokmon card and not a Pokmon ex card
Based on the latest market prices tracked on TCG Stacked, Cloud of Darkness is worth about $0.50 USD for a regular copy and $4.46 USD for a foil copy
The downside is having to discard your current hand but if youre piloting a deck with a highly-specific strategy, knowing when to dump a hand and take a second stab at having the perfect opener grants skill expression not common in the TCG