Surprisingly, for the original Japanese Season 1 TV episodes do not exist.
These are created by fansub groups. They translate the original Japanese script directly. Pokemon Season 1 Subtitles
(subtitles built-in)
can be a bit of a challenge due to the differences between the original Japanese broadcast and the localized English dub. The Challenge: Sub vs. Dub Surprisingly, for the original Japanese Season 1 TV