Pokémon Brilliant Diamond and Shining pearls changed some features and mechanics to accommodate the updated versions that have been added in games that have been out since the player first adventured through Sinnoh in 2006. However, the The developers at ILCA also re-run certain features, making them more faithful to how they were in the original fourth-gen game — including changing the Technics and Hidden Machines.
Technics (TM) and Hidden Machines (HMs) are used to teach compatible Pokémon moves that they may not learn naturally as they level up, even if it’s just for the sake of expanding the set of moves. their own in battle or give the player a way to overcome some obstacles in the underworld.
With HM being phased out entirely to move to an app on Pokétch, ILCA also made it a TM which is a re-use item, breaking after they taught the Pokémon the specified move for the first time since. Black and White. However, certain NPCs, such as Gym Leaders, will give you more than one TM to use, which alleviates the problem somewhat.
This change means that sought-after TMs, such as the TM26 Earthquake, become more valuable again because they cannot be used permanently.
Earthquake is the strongest Ground move in the game and one of the strongest in general. At 100 Base Strength and 100 Accuracy it will deal massive damage to any enemy even when used by a non-Ground.
Players who want to teach their Pokémon this move will need to delve into the Wayward Cave — the smaller section below the Bicycle Path, where you also often go meet a Gible. To get inside you need to gain access to the Strength skill, get through the bike puzzle to the end and head South. A single staircase will bring you to a dead end room with the Earthquake as the only item inside.
You can get more copies of Earthquake TM by visiting the Battle Park and exchanging 80 Battle Points for one at the counter on the right hand side.
https://dotesports.com/pokemon/news/where-to-find-tm26-earthquake-in-pokemon-brilliant-diamond-and-shining-pearl Where to find TM26 Earthquake in Pokémon Brilliant Diamond and Shining Pearl