Reordering a bit.

Project/scripts/check_skip/check_skip.gml

@@ -0,0 +1,27 @@
+var pkmn = global.dexdata[argument0, dex.pokemon];
+var form = global.dexdata[argument0, dex.form];
+var bank = global.dexdata[argument0, dex.bankable];
+
+if (bank == "FALSE")
+    return false;
+
+switch(form)
+{
+    case "MEGA":
+    case "MEGA (X)":
+    case "MEGA (Y)":
+    case "PRIMAL":
+        return false;
+    break;
+}
+
+switch(pkmn)
+{
+    case "ARCEUS":
+    case "SILVALLY":
+        if (form != "NORMAL")
+            return false;
+    break;
+}
+
+return true;

Project/scripts/check_skip/check_skip.yy

@@ -0,0 +1,8 @@
+{
+    "id": "3f1a1302-f9d9-434e-ba08-373fb5c37d32",
+    "modelName": "GMScript",
+    "mvc": "1.0",
+    "name": "check_skip",
+    "IsCompatibility": false,
+    "IsDnD": false
+}