Right now in the 2018 Standard Format the two most powerful decks would be Gardevoir GX/Zoroark GX, and Buzzwole GX/Lycanroc GX, I think this deck including Weavile is already a close 3rd. All you have to do is take a look at these decks and it is no wonder why Weavile is so good, Gardevoir GX, Zoroark GX, and Lycanroc GX all depend on Abilities, same goes for Tapu Lele GX, so a majority of the time most Pokemon in play are cards with Abilities and GX or EX cards, by multiplying 50 damage times the number of your opponent's Pokemon that have Abilities, this card can one hit knock out pretty much anything out there, add a Choice Band to this card and it can easily do 180 damage per turn for only one Energy card. The best thing about this card is that it only allows your opponent to take one Prize card if it is knocked out.
Both Zoroark GX and Weavile are weak to Fighting type Pokemon, which is a big disadvantage, but you can add something like Zoroark from BREAKthrough with its Stand In Ability to quickly knock out a Pokemon that is set up, plus, if you keep Zoroark GX and Weavile on the Bench until you're ready to attack, Buzzwole GX can only do 30 damage to them. So, if you are looking to build a somewhat budget friendly deck, I would highly recommend taking a look at these two cards, Weavile is only a couple of dollars online, and Zoroark GX can be bought directly from a sealed product if you like.
Zoroark GX is the main Pokemon in a deck like this, the reason Zoroark GX is so popular is because it both has a great Ability and a powerful move. Trade, its Ability, allows you to draw two cards every turn, all you have to do is discard one card from your hand. Riotous Beating is its best move, allowing you to attack for one Double Colorless Energy, and if you have a full Bench, allowing you to do 120 damage per turn. Add in the fact that Zoroark GX has a high HP, and you can see why this card is so popular, other than being weak to Fighting type Pokemon, it is perfect, quick on the attack, allows you to draw cards every turn, and packs a major wallop! Plus, if you're building a solely Darkness type deck, it is possible to use Trickster GX too.
Both Sneasel and Weavile are available in Ultra Prism. One thing I like about Sneasel is that it has 70 HP, so if you are forced to put it into the Active Pokemon spot to start the game, it can last a turn without getting knocked out, plus, it needs 3 attacks by Buzzwole GX on the Bench to get knocked out. And if the chips fall correctly, you can really set back your opponent if you can use Sneaky Smash and remove an Energy they put into play. Weavile doesn't have an above average HP by any means, but it does have two moves that both only require one Energy card to use. In a deck like this one, with Zoroark GX, you're going to be using 4 Double Colorless Energy and the rest Darkness Energy, so either move on this card shouldn't be a problem to use. Evil Admonition is the move to use on Weavile as it does 50 damage times the number of your opponent's Pokemon that have Abilities on them. Early in a game, you could easily knock out the defending Pokemon by doing only 100 damage. Even if Weavile is knocked out, your opponent only gets one Prize card, and using something like Rescue Stretcher, you can get both cards back into your deck. I think it will be very advantageous in the future to have powerful attackers in your deck that only count as one Prize card when knocked out. Icy Wind isn't a terrible move either, as it can put the defending Pokemon to Sleep and give you more time to set up your Pokemon.
Overall, I would highly recommend at least testing out a deck built around Zoroark GX and Weavile, like I said, this is a cheaper deck to build and it is a deck that can still win battles and do very well! I look forward to reviewing some Ultra Prism decks on my channel, and this deck will certainly be one of them.