>>41349865You could take, for example, a Pelipper or an Unfezant male with a Roost and breed it with a Rookidee to get that egg move. Then you could “pass” Roost to your main Corviknight by putting it and the bred mom with the move into the Nursery together. You might have to evolve the Rookidee, but I’m not positive about that. The major downside here is that Roost is generally learned in the 40s or 50s for a lot of Pokémon now.
>>41349865Tough to do that without Spikes, Stealth Rock, or Whirlwind. Corviknight is pretty solid competitively even without hazards, but it’s quite different from Skarm. Ingame the best bet is probably boosting with coverage moves and possible Roost or Defog if you feel you need it.
>>41350169I was led to believe it’s a Psyshock situation where it literally uses Defense to attack, but I am not 100% certain that it’s more like Electro Ball or Heavy Slam without the difference-between-user-and-opponent quirk, where it uses a range of values.