Basic monsters end being a joke very quickly, mostly because their low BP compared with most of new monsters from expansions.
Getting the idea from the APP of advanced skeletons (can attack diagonally) anr goblins (can move and attack and continue moving) it would be cool to have the same for the other monsters. As a kid I used Battlemaster goblins and orcs as armored and gave them 2BP. So, something like that.
Advanced Dread warriors would be Doom guards (+1 MOV, +2 DEF).
Advanced gargoyles would be Guardians, +2BP and Inmune to magic , like the one in Kellars keep.
Advanced zombies and mummies could have +1 attack and defense or Regeneration, they defend from all skulls with just 1 Black Shield, so they are quite hard to destroy.
Advanced abominations should have frenzy, they add +1 attack and defense if they are below its full Body points.
Any more ideas?