After picking up Series 4 at my local TRU today, I got characters that are normally in Wave 2. Pootato and Zapped Lamp. This means that the US release of Series 4 has all characters in one big wave. It's not just S4, because Trash Wheels did the same thing. I can't be 100% certain, though. I think the delay of Series 3 Wave 2 (In the US) was a reason for this. I don't know about AU, though. S5 has waves for them.