Regulation Marks (D–H): What It Means and How to Spot It

• Definition of the regulation mark: a letter printed right next to the set symbol/code that indicates whether the card is legal for tournament play
• Officially confirmed (pokemon.com): players must check the regulation mark at the bottom of the card to determine whether it can be used in the current format, independent of which set it belongs to
• 2021-23 season: cards with mark D or later are legal, up through Crown Zenith
• 2023-24 season: cards with mark E or later are legal, up through Paldean Fates
• 2024-25 season: cards with mark F or later are legal, up through Prismatic Evolutions
• 2025-26 season: cards with mark G or later are legal, up through Ascended Heroes
• Starting the 2026-27 season: cards with mark H or later are legal
• The letter D first appeared in the Sword & Shield set (the international release's first use of the regulation mark)

• Set symbol / Set Identifier: Both sit close together near the bottom of the card, but the set symbol/code indicates which set the card belongs to, while the regulation mark indicates whether it is legal in the current format; the former is a graphic or a three-letter code, while the latter is always a single capital letter.

Basic Energy cards carry no regulation mark and are therefore never affected by format rotation; this point is compiled from the Bulbapedia article as a whole rather than from a single directly quotable sentence, so it is not listed separately under how_to_identify (see unverified_fields). No clear, unambiguous verbatim source was found for exactly which set each of E/F/G first appeared in (there is a risk of confusion with the same-named 'Regulation Set G' concept from the Pokémon Scarlet & Violet video game's battle rules, which has been excluded as a misuse); only the fact of each season's 'minimum legal letter plus cutoff set' has been confirmed.

• Bottom-left or bottom-right corner: the set symbol and the collector number (e.g. 4/102) tell you the set; older cards have no symbol at all, which itself narrows them to Base Set.
• Left of the number: a 1st Edition stamp, if present, sits below the art on WOTC-era cards.
• Regulation mark (a letter in a box near the bottom, D through H so far) dates modern cards to a two-year window.
• Back of the card: the blue Poké Ball back has changed little since 1999; a washed-out, blurry or wrongly colored back is the first sign of a fake.

Lay the card flat on a dark surface in daylight, straight on, with the whole card in frame, then a close-up of the bottom edge where the set symbol, number and any edition stamp sit. Tilt holo cards under the light for a second shot to show the foil pattern. Photograph the back too. The app reads the card and set; the edition and rarity checks above tell you which version you have.