It was only available inside random booster packs of the SM#8 Explosive Impact series that was released in Japan, in September, 2018
No one else will be able to verify you did it correctly, but we'll give you the benefit of the doubt
Put a Pokemon or a Supporter card from your discard pile into your hand
There's plenty of other ways to use The Master, Multiplied other than copying himself
When you flicker a creature that was haunted, its exiled from the battlefield and then returned to its original state, which means that alterations to it, like counters, damage, and, in this case, the haunt ability, are lost
That said, cards like Barbarian Class increase the odds for the better