These came from the very first Pokemon press kit released in the west, before the name localizations were finalized. It’s likely that it was given out in early-mid 1998. Unfortunately, I don’t personally own the entire press kit, but I was able to obtain and upload scans of the whole thing.
As stated in small text at the bottom of each page, the names were, in fact, subject to change. A few highlights: Kara-tee, Kung-foo, and Ju-doh instead of Machop, Machoke, and Machamp; Skulkraken for Gyarados; Ess and Kargo for Omanyte and Omastar; and perhaps the most iconic, NY and LA for Koffing and Weezing, which will never not be funny. But it is pretty obvious as to why that didn’t stick.