Maybe you should provide a little more info, a possible deck list etc. That would help
To answer it as short as your question: no(t entirely). Because you will loose against decks which doesn't play that much abilities. On the other hand: a lot of decks at the moment do. But I feel like you should have at least some other attackers. Would you like to make it Koko - Shrine - Tapu Lele (non-GX, Magical Swap)? Or what Pokémon would you pair it with? Garbodor?
And you may struggle to set up in you need to set up Magcargo and Swampert (personal experience), but that depends very much on your deck list. So give us a list, and we can provide help.
I say go for it. Swampert draws like a maniac, Magcargo stacks the deck for any card you want, and Weavile attacks. This deck can work as a stall deck with Shrine. If you have (hard to actually get example) 3 Magcargo benched and a single Swampert, you effectively have Steven’s Resolve every turn. Three of any cards in your deck opens a host of new things you can do with a toolbox of cards. I have to agree with @lukas2aces, though, it will be a doozy to set up. If you can do it, you’re set to go.
Moved thread from the Deck Garage to the Competitive Play Forum because the OP is asking about the idea of a deck and not providing a list and looking for advice~
The combo of Swampert and Magcargo can work. I'm just not sure if Weavile should be the beneficiary of that combo. Maybe Golisopod or Lucario would suit it better?