?/ is very unique, being that it has infinite sprites. Its sprites are ever changing due to the fact that the game pulls its sprite data from a changing value, presumably from location data. Despite this, its back sprite is constant.
When ?/'s Pokédex entry is viewed, it will display "?/ is trying to learn" or "?/ learned MASTER BALL!" for a very long amount of time; the game could then freeze or show the PLEASE WAIT! screen for connecting to other players.
When an opponent puts ?/ into battle, the game will continually display "?/ learned _"; however, this does not always happen.
After battling ?/ the player can become offset, meaning that the player will shift slightly to the right and will not line up with things such as doors, and can appear to walk through some objects on the right side of the screen.
If the player patches the rival to have this Pokémon, after defeating him, the rival's overworld sprite will become a glitch block of lines.
In ?/'s Pokédex entry, the game may emit high-frequency noises.