The glitch allows the player to capture Pokémon from a Trainer with at least two Pokémon on their team, including an ordinary Trainer or a Battle Tower Pokémon such as level 100 Linoone, Hariyama, Dustox, etc.
The Pokémon from the Battle Tower can be nicknamed and will not turn into a Bad Egg, but the Pokémon from other Trainers may become Bad Eggs.
However, you can exploit this to spread Pokérus by battling with the Bad Egg in the party, because after the battle ends the Pokérus has a chance to spread (even though the original affected Pokémon was a Bad Egg).
On August 1, 2014, G- Mizuka uploaded a video showing the glitch in Japanese Pokémon Ruby.
On July 17, 2014, SailorJupiter confirmed that the Latios glitch in fact works for US English Ruby in addition to the Japanese version.
To perform this glitch, the player must lose (or win?) against a Trainer with at least two Pokémon, and then encounter Latios or Latias without encountering another Pokémon in between (very important).
The player should defeat the Latios/Latias, and this will cause a "PkMn Trainer" with a blank name with a team based on the Battle Tower Trainer you lost against to send one of two of their Pokémon (the game thinks that you KOd one of them).
This Pokémon will flee like Latios/Latias, so it is a good idea to use Mean Look or Spider Web against them if you cannot catch one with a Master Ball. If that Pokémon is defeated, the Trainer will send out another one of their Pokémon, which can be captured and can flee like the first Pokémon after Latios/Latias faints.
If the Trainer is defeated, no victory text will appear. The player can gain experience from the Battle Tower Pokémon if a Pokémon participated that is below level 100, and if that Pokémon gains experience, the wild Pokémon victory music may play and stick, even if the battle hasn't ended yet.
The origin of a Pokémon obtained from a Battle Tower Trainer is stated to be "BATTLE TOWER (met)".