The number of cards that can actually meet PSAs highest standard is incredibly low
Frequently Asked Questions How many cards are in the XY - Ancient Origins master set? The XY - Ancient Origins master set is 174 cards: 98 base cards, 73 reverse holofoils, and 2 secret rares and special-art cards
The problem with Battle of Wits is that when you consider you will need 200 cards in your deck once it hits the battlefield and that it might take several (or many) turns to get Battle of Wits on the battlefield, you will need to play somewhere around 240 cards to make Battle of Wits work, which means you're increasing your deck size by 300%, which in turn leads to a massive drop in consistency, to the point where Battle of Wits simply isn't worth the cost in competitive decks
Unlike other meta leaders Pikachu ex relies on having a full Bench, as its attack does 30 damage times the number of Pokmon there
You can then also spend either black and tap it to either exile an instant or sorcery to make your opponents lose two life, or green and tap it to exile a creature card from a graveyard to gain two life
Umori also comically won a constructed event I did involving a deck built around each companion and using the original rules