I have to agree with the above 3. There are almost no decks that lose out on something important by discarding cards. Computer Search is too useful and too good compared to a card like master ball.
Master Ball would be great in a deck that has zero consistency issues.
Master Ball should've been able to search your Deck or Prizes for a Pokemon (replacing it with whatever), since Master Ball is supposed to catch a Pokemon without fail.
Don't think I'd go as far as to call Balls a subclass. I thought there was more support but a pokepedia search only showed me Apricorn Maker. In this format, that card could be really good but I think the situation is the same. Back then, we would have rather played Copycat, POR, Juggler. Now, we would end up playing Juniper, N, even Skyla and Bicycle.