NINTEN and SONY.

[Takahashi2212]

"An unused default name for Red in the English Generation I games was "NINTEN". Conversely, Blue's unused default name is "SONY". While normally unviewable, changing a few addresses within the game's code can allow for these names to appear as shown here. This references the fact that in the years surrounding the releases of the Generation I games, Sony was Nintendo's main competition. Also Ninten is the default name of the main protagonist of Mother, another Nintendo game. Many people who worked on Mother also worked on Pokémon."

Source:http://bulbapedia.bulbagarden.net/wiki/Red_(game)