With this script you can reduce the amount of damage taken by an element that is a weakness. The picture is because Rhyperior has the ability Solid Rock an ability that does that.
How does this work?
From the Bulbapedia page on Solid Rock
“Solid Rock reduces super effective damage by ¼. A move that would deal 2× damage will instead deal 1.5× damage, and a move that would deal 4× will instead deal 3×.”
<weak reduce> Sets weakness reduction
<weak reductions rate: x%> The reduction rate