c has a very long, spaced-out name that takes up many rows and forces the player to press A or B multiple times when viewing it in any way. The name will also take up some of the move names on its stats screen, however this is not harmful to the game. These issues can be fixed by renaming c.
This glitch Pokémon article is part of Project GlitchDex, a Bulbapedia project that aims to write comprehensive articles on glitches in the Pokémon games.