All 1156 cards of the twelve Japanese releases are listed, and none of them is reconstructed from a list of names. The counts match the card database that holds the Japanese scans: 70 in January, 69 in February, 116 in March, 69 in April, 69 in late April, 115 in May, 80 in July, 75 in August, 117 in September, 226 in October and 75 + 75 in December. 249 of them print past the end of their own set and are shown as printed rather than normalised — every one is a full-art, gold, Hyper Rare or, in one case, a Character Rare card.
The Japanese printing is the first-hand source here. Type, HP, retreat cost, illustrator, every attack with its cost, and the rules text of every Ability are read from a Japanese listing of the card. English supplies two things only: the official English card name, and the verdict on whether the English printing is the same card. All 255 Trainers and 15 Energy cards carry the name printed on the Japanese card, and every Pokémon name was read from the card page rather than from a species list.
December’s pair is the source trap of the year and it is stated rather than hidden. Sword and Shield are listed as empty shells in the Japanese card database — the set exists, cards comes back empty, and a single card URL answers 404 — so the 150 cards were read from the Japanese card list instead, and that is where the type, the attacks and the illustrator come from. The same database also reports the two packs as 60 cards each; the printed sets are 60 numbered plus 15 secrets, 75 either way, and this page uses the 75.
54 cards carry no rarity at all, and that is the card, not a gap in the data. They are the reprints inside October’s Tag All Stars: a reprint card in that product is printed without a rarity symbol, so this page leaves the field empty rather than inventing one. It is the same rule as the shiny cards of 2018, which also print with no symbol.
The 17 Prism Star cards are the last of their kind, and the count comes from the printed name. The card database does not flag ◇ on any Japanese card at all; the symbol is part of the name as printed, so every one of these was read off the card name rather than from a field. All seventeen are reprints inside Tag All Stars, and no new ◇ is printed in either language after 4 October 2019.
The pairing verdict is stated for every card. 739 of the 1156 are printed in English inside 2019, 150 are printed in February 2020 — 72 of Sword, all 75 of Shield, and three cards of July’s Remix Bout — 220 are reprints of cards English had already printed, and 47 never printed in English at all. There are 9 ’same species, different card’ cases, marked as such rather than folded into the count: a card that is not the same card is not a printing. Japan prints 1156 cards in 2019 and English prints 1140, and the gap is a set of reprint and secret cards that never crossed rather than an error.
Two things are incomplete and are declared here. 42 Pokémon cards in this year carry no illustrator credit — they are all the GX and Tag Team secret printings of the numbered sets, where neither the card database nor the Japanese listing records an artist, and none has been guessed. And the December pair is counted as 2019 because it went on sale on 6 December 2019 in Japan, even though its English edition is a 2020 product: the same rule this site used for the 12-17 release of 2010.