In this particular case you're good to go. The Dunlop wah takes the same type of power supply as most Boss pedals. And most (small, analog) Boss pedals draw only a small amount of current (amperage, "mA"), so they should be fine on the daisy chain off the TU-2. What you do is look in the manufacturer's specs for the current draw of each pedal you plan to hook up, and then add all of those current amounts together. Then look at the amount of current the power supply is capable of putting out. Make sure the first number is smaller than the second one.
Be careful with the larger question of whether "all" power supplies are interchangeable, because you have to match up voltage, AC vs. DC, current needed/supplied, and polarity.
Power supplies interchangable? 
