Pokmon TCG Pocket has a big retention problem, developers reveal I'm sort of a hater, so nobody listened to me when I said this myself in the past
The deck can either trade with Vivi's creatures or trample over them, letting you constantly deal damage to them
Also, as your foes attack each other, they (and you) will draw a card and lose a life, and with that being doubled with Isshin you could get a lot of cards drawn
If your opponent isnt playing white creatures, he likely doesnt have any plains to cast them with, in which case Aysen Highway doesnt help you at all
While Draft Booster packs usually have ten common cards ( Baldurs Gate has thirteen), Set Booster packs usually top off at four
And having just one colored mana, its easy to cast