In order to obtain Magmortar in Pokémon Brilliant Diamond and Shining Pearl, players will first need to find and catch a Magby. Players that own Pokémon Brilliant Diamond will need to trade for a Magby, Magmar, or Magmortar in order to obtain them because they are exclusive to the Pokémon Shining Pearl version. After catching one of the previous forms of Magmortar, players will then need to obtain a Magmarizer and trade to evolve their Pokémon into Magmortar.
Magby can be found in three different locations in Pokémon Shining Pearl's Grand Underground. Players will need to travel to either a Volcanic Cave, Sandsear Cave, or Typhlo Cave and keep going in and out until a Magby appears. Magby needs to be found and caught until players obtain one that's holding a Magmarizer. Unfortunately, there's no other way to get this item except to find a Magby in Pokémon BDSP that's holding a Magmarizer. Once players have a Magby and the Magmarizer, they can work towards obtaining a Magmortar.
Magby will evolve into Magmar at level 30, and there are no other requirements besides the level. However, to evolve Magmar into Magmortar, players will need to have the Magmarizer and complete a trade so Magmar can evolve in Pokémon BDSP. Regardless of the game version, Magmar needs to be traded to the player while it's holding a Magmarizer for them to get a Magmortar.
Trading to Get a Magmortar in Pokémon Brilliant Diamond and Shining Pearl
After visiting the Grand Underground in Pokémon BDSP and catching a Magby with a Magmarizer, players will need to find another trainer to trade with. Fortunately, players have come up with a way to find trades based on the Pokémon's PokéDex number. Those that have Pokémon Shining Pearl can use the room code 0126-0126 to start the trade. This will indicate to another trainer that the player wants to trade a Magmar holding a Magmarizer for the same Pokémon and item. Once received, Magmar will automatically evolve into Magmortar.
Players that have Pokémon Brilliant Diamond can still obtain a Magmortar via trade, but they will need to trade another Pokémon for it. The most common Pokémon to trade for a Magmortar is Electivire since it's exclusive to Pokémon Brilliant Diamond. Electivire is considered the counterpart to Magmortar, so players looking to complete the trade should use the code 0125-0126. This indicates the player has an Electabuzz holding an Electirizer and they are looking for another trainer that has a Magmar holding a Magmarizer.
Completing trades for Magmortar should be fairly easy using specific room codes, but if players are having trouble connecting, then they can try to start a random trade and offer the Magmar. Trades always need to be confirmed before they're completed, so players won't risk losing their Magmar by looking for a random trade. Once the offer is completed, players will have a Magmortar in Pokémon BDSP.
Pokémon Brilliant Diamond and Shining Pearl are available for Nintendo Switch.