Wave 3 you move to season 2. Core Thunderzords. You can release Automorphins of White Ranger, and Rocky/Aisha/Adam versions of Red/Yellow/Black. That's only four new good guy figures though. Could this be where Bulk and Skull slot in? Maybe an Automorphin Incredible Bulkster and Super Skull? For villains Zedd, Z Putty, and Pirantis Head seem like the most sensible choices to ring in the second second. There's Saba for role play, and I guess you can start to release the Power Weapons here. Maybe spread them out over the remaining MMPR waves. They can do some Thunderbikes for vehicles I suppose.

Wave 4 you finish season 2 with Tigerzord, maybe Tor, MAYBE Serpentera. Finish Thunder Bikes, a couple more Power Weapons. For villains my wishful thinking would be Finster, Scorpina, and a monster of the day (preferably from Dairanger). Scorpina may be a stretch since she only appears in two season 2 episodes (and the first appearance is very brief), but she does play a major role in "Goldar's Vice Versa", and is essentially the monster of the day for the episode, so I think that warrants including her here. For good guy figures... I guess if they did fully civilian Rangers in wave two they could do Rocky, Adam, Aisha, and White Tommy here, and if they did an Automorphin Bulkster and Super Skull in wave 3, I suppose they could do normal versions here. There's just not much else to work with figure wise for good guys. I guess they could also do Wild West Rangers...