I know the website said it's on whatever route, but do you need something special? And what to do to get it?
You can get the Manectite on the Northend of the Cycling road. Enter from the northern building and go under the bridge, the stone is next to the Beauty. There are apparently no special conditions, except having to fight the Beauty.
Hope I helped!
The Manectite is on the ground off a small hidden pathway just before the upward slope of Cycling Road. You'll need to enter Cycling road from the northern side on Route 110. This means you also need a Bicycle from the bike shop in Mauville.
You'll get it just by finding it on the ground as a sparkling square and interacting with it. But you will need to battle a trainer first (Beauty Melissa). Here is a guide with step-by-step directions if needed: https://guidestrats.com/pokemon-oras-manectite/
And here's a screenshot of the exact mega stone location:
(Source: Guide Strats)
