Quaquaval Battle Deck

I'm new here. Was winning 0%, started playing quaquaval deck and got win rate up above 90% until my 45th match now I'm consistently getting outclassed.
Two questions:
1) is quaquaval deck actually viable or was I getting lucky
2) does anyone know the matchmaking algo in casual mode?
Answers
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Casual mode is very variable, an upside is you don't just get meta decks to play against, the downside is you can play against decks that are broken so the win rate is a not a good indicator of deck strength. There's a new league starting soon, if you can maintain a win rate above 50% all the way up then you know you've built a decent deck. If you don't want to play too often measure yourself against the meta decks you meet. (Search pokemon meta decks for the latest rotation lists).
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