TM60 Quash can be bought for 36 Battle Points (BP) at an Exchange Service Corner within the Battle Subway. The Battle Subway is located in the center of Nimbasa City.
You’ll be able to reach Nimbasa City after defeating Gym Leader Burgh in Castelia City.
You’ll get awarded BP based on your win streak and the difficulty of each battle in the Battle Subway. Several TMs can be purchased with BP at an Exchange Service Corner on each subway.
And as for the move itself:
TM60 Quash is a Dark-type move that forces the target to go last. It is only really effective in Double battles and Triple battles.
TM60 Quash Location (Step-by-Step)
Step 1: Head east from the Nimbasa City Pokémon Center
Step 2: The Battle Subway is next to the Pokémon Center on the right. Enter the building.
Step 3: The entrance to the Battle Subway leads to a large platform with seven subway trains. Enter any subway you’d like – they all have an Exchange Service Corner.
Step 4: After entering the subway, you’ll see the Exchange Service Corner in the northwest corner.
Speak to the clerk on the left.
Step 5: TM60 Quash can be purchased from this clerk for 48BP.
Along with TM60 Quash, this clerk also sells the following TMs:
|TM23 Smack Down
|TM34 Sludge Wave
|TM51 Ally Switch
|TM77 Psych Up
Quash Details + Uses
|Quash Move Details
Quash is a non-damaging Dark-type move that forces its target to go last in battle. It really only has use in Double or Triple battles, since it becomes redundant in a Singles battle.
And even when used in a multi battle, Quash is very situational and borderline useless.
If the user Pokémon is fast enough to use Quash on its target, then the target Pokémon is more likely to be slower anyways.
The move also has 0 Priority, which further lends to its uselessness.
Quash is typically only used in one situation: by a Murkrow with the Prankster ability.
This ability increases the Priority of all status moves by 1, providing a slight boost to Quash’s usability. And even then, Murkrow learns Quash at level 65, removing the need to purchase the TM anyways.