Deep Sea Scale

[Mr. Suplado]

Deep Sea Scale: 
Celestine Mountain B3F, enter from the Celestine Cascade entrance or reaching Celestine F1 from Citrine or Ametrine, go down the Waterfall at the right, go down the Waterfall in B1F to reach B2F OR enter from the North Aventurine Woods after completing E15, then use the Strength glitch to go to the left of the Ice-Strength puzzle and reach the Dive spot, go to the top right seaweed patch and go through a discrete cave opening on the floor just above the seaweed patch that you need to surf over it going downwards, resurface and it's on the ice-skating area in front of the X-Door
Held by wild Chinchou, Lanturn, Relicanth and Blue-Stripped Basculin

 

 

I read that info on how to get deep sea scale... but how to use the Strength glitch is there any video or tutorial?

[Walpurgis]

The strength glitch is basically pushing the boulder as far as you can, save and then when you load the game again the boulder position resets and you're on the other side. It has been known for a long time, so I don't know if it's still a thing. If it doesn't work since you already have access to dive you could just use a pokemon with compound eyes to boost the likelihood of the deep sea scale appearing as a held item by wild pokemon and get it that way.