It's possible to trigger one of three error messages at the title screen if you have attached a Nintendo 64 Disk Drive (N64DD), suggesting that an expansion disk for the game was planned at one point.

The three messages which can appear are:
• Error: 41 DEVICE_COMMUNICATION_FAILURE N64 Disk Drive or N64 Control Deck may not be connected properly.
• Error: 43 POWERONRESET_DEVICERESET_OCCURED N64 Disk Drive may have broken down.
• Error: 44 RAMPACK_NOT_CONNECTED Jumper Pack may be left in N64 Control Deck.

Pocket Monsters Stadium was heavily influenced by the early competitive Pokémon scene and Nintendo Cup '97, the first Pokémon tournament officially hosted by Nintendo. Most of the 40 playable Pokémon in the game were chosen based on their presence in official tournaments, with a few added to add type variety. Furthermore, the NPC trainers of the in-game tournaments use the names and teams of real-life competitors at that time.

HAL Laboratory president and co-producer Satoru Iwata was not provided with a specification document regarding the battle logic from Pokémon Red and Green when he needed to port it to the Nintendo 64 for the development of Pocket Monsters Stadium. According to one of Red and Green's programmers Shigeki Morimoto and series producer Tsunekazu Ishihara, Iwata managed to finish reworking the code for the battle engine and got it running on the console in about a week.