Gardevoir is the most played Expanded deck right now, at 7.2% of the field across 5 tournaments in the last 3 days. Its 6 tournament lists average a 56.5% win rate, with a best finish of 2nd. 23 core cards show up in at least 70% of lists, including Ralts, Kirlia and Cresselia.
Appear in 70%+ of decklists, so they are near-essential for the archetype
Appear in 40% to 70% of decklists, so they are common but swappable
Not enough data for matchup analysis
Public decks built around this archetype