OLDEN (also known as INOL) is a notorious glitch that manifested in Bugsy's gym during the events of Twitch Plays Pokémon Crystal Anniversary's 3rd day. When EVAN fought BUG CATCHER JOSH, right after EVAN sent out his pokemon, OLDEN appeared, filling up the screen as shown and crashing the game numerous times. Naturally, the chat was rather spooked.
Later on, after a patch done by The Streamer while drunk, during Day 11, EVAN came face to face with a glitched female trainer caused by a tile error. The chat acknowledged the glitched trainer (who had no name) as OLDEN.
OLDEN, during battle, had 6 pokemon, although EVAN could only defeat one pokemon (a Gastly at level 100) before losing to Golbat (also at level 100). Two are known at this time, the Gastly and the Golbat, while the other four were not discovered during gameplay. The glitch Pokemon had strange movesets, such as Extremespeed and Tackle on Gastly, Wrap and Rollout on Golbat. The AI chose these moves exclusively, resulting in EVAN's defeat, so it is not known what other moves the trainer may have taught their Pokemon.
During the battle, OLDEN glitched EVAN's name to "ECBB9CBB1CB?9CB682807CB78200336F0231?CB37CD03391?CD03". After the battle, EVAN blacked out.
Streamer shortly reverted the game back to before the battle, and sarcastically stated that he had to patch TPP while drunk more often.
How It Happened Edit
The exact cause of the glitch was determined to be a glitched map error caused by modifying the location of EVAN (the player character) without updating the pointers in the code. Because the map size was modified and the code was structured to point to a certain location in memory for trainer data, the location where trainer data was found was incorrect. Because the location of trainer data held incorrect data (due to the map not being properly reloaded after patching it), strange data was read back as the aforementioned gltitch trainer. Which portion of the game code was read as trainer data is unknown at this time, but AI logging may hold the key to discovering the other four Pokemon.