 The Japanese version of "Crystal" which had a mobile phone adapter allowed for players to challenge other players to Battle Tower fights.The next Battle Towers appear in "Ruby" and "Sapphire", which is similar to the "Crystal" Battle Tower, and in "Diamond" and "Pearl", which has a boss character and a point system similar to the Battle Frontiers.The was introduced in "Pokémon Emerald", replacing the Battle Tower as found in the "Ruby" and "Sapphire" games.