Copycat vs. Serena's Choice in Blastoise Decks

TLDR: Serena's Choice is better. It won 55.9% of its 20,000 games vs Copycat only winning 52.7% of the time. This blog post explains the analysis.

Introduction

Blastoise is my boi. That's why as soon as I pulled two from Dual Fusion, I started trying to make it work.

I started by searching for decks in the deck search and found a few archetypes to start working on. Ideas included Vaporeon, Suicune, Mega Blastoise ex, or a Eiscue-Oricorio one.

I manually ran a couple games, to get a rough idea of each. This is what I learned:

• Mega Blastoise ex: The idea of having a prize map of two 1-point Blastoise into a 3-point Mega Blastoise ex sounded interesting. But to do this one needs two scarfs, and having the 1-Point Blastoise go first, means its hard to transfer the energies to the Mega Blastoise. So this idea... discarded.
• Suicune: Is good for deck speed, but often gives the opponent a Suicune > Blastoise/Squirtle 3 point prize map that makes it hard to win with. Giant Capes are important to have Suicune avoid the 140HP breakpoint, and thus there is not much room for tools to address starting with Squirtle.
• Vaporeon: It was hard to make this work. To have this be consistent one seems to need the speed of Suicune, and even then its hard to survive long enough to be able to power up Mega Blastoise ex.
• Elemental Switch: I think this is strictly better than Eevee + Vaporeon, but after say 10 games of testing, I never managed to get Mega Blastoise online with 6 energies.

So lastly, I settled on the Eiscue version. Removed the Oricorio and started testing Eiscue-Blastoise only. It started feeling good, for except the prize map was 1-1-1, and the damage output wasn't high. So I needed a ex+ pokemon that could hit hard and possibly retreat fast. Its ok if it needs energy, since Eiscue its often there to be sacked, and Blastoise charges himself.

Using pokemon card search one quickly sees that the only Water Basic ex with low retreat and high damage is Chien-Pao ex. That's when I basically settled on the following decklist:

It also uses the insight that most champion decks have 7 Pokemon (more on that in a later blog post!).

Last Mile Optimization

Now... although I roughly knew I was close to a good deck, I wanted something fully optimized.

That's why I reached out to using deckgym-core, an open-source PTCGP simulator that allows one to run thousands of games with different deck variants and collect winrates.

I decided to focus on the Copycat slots, since the rest felt fairly core, and I've been particularly curious how does Copycat and Serena's Choice compare. Is one better than the other?

Experiment Setup

We built 3 variants of the same deck. The only difference is 2 cards:

• 2 Copycat
• 1 Copycat + 1 Serena’s Choice
• 2 Serena’s Choice

Everything else stayed the same:

• Same 18 other cards.
• Same opponents: the 10 most played decks, 2,000 games against each.
• Same player: a bot that plays every version the same way.
• Same luck: every version drew the same shuffles.

We made each variant play 20,000 games while keeping track of how many it won. The idea is that if one variant wins more, it has to be because of those 2 cards.

Results

2 Serena's Choice is best! It achieved a 55.9% win rate against the current Top 10 meta decks.

Serena's Choice is ahead in all 10 matchups:

Conclusion

I think this has to do with the fact that Blastoise requires the combination of two cards to have it be online (Rare Candy + Blastoise), and Serena's Choice can give you exactly that, a stable way to find the one you are missing. Copycat also depends on the opponent having many cards in hand to be effective.

So final recommendation, is to include Serena's Choice, and use it to find the missing piece to bring Blastoise online!

Hope you found this useful. Happy deck building! 🙌