Can anyone advise on the following please?
Does befuddling Strike stack with the Unchained rogue's debilitating injury (disorientated) ?
Does the ninja trick pressure points stack with crippling strike?
Could all of those be stacked together?
Some talents add effects to a rogue's sneak attack. Only one of these talents can be applied to an individual attack and the decision must be made before the attack roll is made.
Ninja trick has similar terminology.
You can only add one talent/trick that affects sneak attack (without an ability that says otherwise). So you can only add one of befuddling strike/pressure points/crippling strike.You can use debilitating injury with any one of those as it is not a trick or a talent.
Penalties stack.
Technically if you could multi-class ninja rogue then you could stack a ninja trick and a talent together. Also a permissive reading would allow a ninja trick obtained via a rogue talent (or vice versa) might allow you to use both together, but I would still treat it as a talent if I were GMing.