Where it comes from
Nintendo consolidated financial results FY ended Mar 2001 (English) Nintendo Co., Ltd. · 24 May 2001 Open the original ↗
The line in the source
Pokémon USA, Inc. and The Pokémon Company LLC became affiliates because The Pokémon Company fully owns them; trade name changed from Pocket Monster Center Co., Ltd. to The Pokémon Company.
In English
Per Nintendo FY3/2001 English results (fetch-tool summary of notes; wording partly paraphrased). Dates Pokémon USA's existence to by Mar 2001.