I was able to get it working!
class ScatterTrees extends Sup.Behavior { trees = []; treeCount = 50; start() { for (var i = 0; i < this.treeCount; i++){ Sup.appendScene("Plants")[0].arcadeBody2D.warpPosition(Sup.Math.Random.float(-5, 5),Sup.Math.Random.float(-5, 5)); } } update() { } } Sup.registerBehavior(ScatterTrees);