There's many common terms used casually in online listings with little (if any) explanation. To help remedy that, here is a complete list (as I find them!). Words without a definition, I am still trying to determine...
Amada: a company that works with Nintendo to create Pokémon merch, mostly stickers with some menko; since 2005 a subsidiary company Ensky handles this work; for more information: Amada
batomen: short for "battle menko"; a kind of menko meant to be used with an electronic device; for more information: Batomen
bettan: another term for the game of Menko, which is played via cards/chips also known as menko; for more information: Menko
carddass (カードダス): sometimes "cardass"; cards gotten from vending machines; for more information: Carddass
CoroCoro Comics: often written as "Corocoro"; a magazine; frequent collaborator with Nintendo; frequent source for promotional cards and other items
Ensky (エンスカイ): a subsidiary company owned by Amada, created June 2005, that began working with Nintendo in 2005 to create Pokémon sticker merch; for more information: Amada
furoku (ふろく): literally "appendix"; magazine freebies; free promotional items included in magazine issues (e.g. cards, stamps, etc)
ginpika (ぎんピカ): literally "silver shine"; shiny, as in the item's appearance, most often via a metal/faux-metal foil
hikuzo-kun (ひくぞーくん): Best I can tell, this is a sticker brand name manufactured by Ensky (which itself is a sub-company of Amada)
himitsu (ひみつ): literally "secret"; possibly refers to blind box items or similar, where the buyer doesn't know the exact item of a set that will be gotten(?)
jiten (事典): literally "encyclopedia," similar to "zukan"; often refers to a book of information (e.g. character profiles, story summaries, interviews, etc)
kai (改): literally "revised" or "improved"; often used in sequel titles to imply an improvement.
kaku (角): literally "rectangular"; often used in conjunction with menko (e.g. "kaku menko"), meant to differentiate between rectangular, square, and circular-shaped menko
maru (まる): literally "circular"; often used in conjunction with menko (e.g. "maru menko"), meant to differentiate between rectangular, square, and circular-shaped menko; can also be used for "hyper," as in a larger size
menko (めんこ): rectangular cards or circular chips used to play the game of Menko; for more information: Menko
Nagatanien: a food and drink company; common products include tea and packaged curry; often collaborates to include Pokémon items in its product packaging
patchin: another term for the game of Menko, which is played via cards/chips also known as menko
Pogs: a game similar to Menko; for more information: Pogs
retsuden (烈伝): literally "intense story"; best I can tell, this is just a generic packaging term used to hype up the product, doesn't inherently mean anything
seal (シール): literally "sticker"
sealdass (シールダス): stickers and sticker sheets gotten from vending machines; for more information: Sealdass
Shogakukan: a publishing company; in charge of Pokémon books, manga, and anime merch; often found in the copyright and thus included in listing titles; sometimes it can mean the item was a free promotional item in one of the Shogakukan learning magazines, unfortunately have to use context clues; for more information on the magazine: Shogakukan Grade-Specific Learning Magazine
Staks: a game similar to Menko, but with magnetized chips; for more information: Staks
Takara: see Tomy
Tazos: a game similar to Menko, made by the Frito-Lay company; for more information: Tazos
Televi-kun (てれびくん): also written as "terebikun"; a magazine; frequent collaborator with Nintendo; frequent source for promotional cards and other items
Tomy: a toy manufacturer; worked with Nintendo to create toys/etc; called Takara Tomy in Japanese, thus listings might use "Takara," "Tomy," and combinations thereof
Topsun: a company that worked with Nintendo to create Pokémon merch, mostly collectible cards; for merch made after Fall 1998, may be referred to as "Top," not to be confused with the American company The Topps Company, Inc.; for more information: Topsun
zukan (図鑑): literally "illustrated reference book" (e.g. a field guide or bestiary), similar to "jiten"; in a Pokémon-context it means Pokédex; for item listings, this is usually a sign that the item was part of a larger set (likely encompassing the Pokédex of any given generation)
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