Add Viper for the 4th and blammo, you have what I have been saying! ^-^
It's the perfect set.
Then, if they wanna go nuts and it sells, do an environment set with Eels, Snow Serpents, Range Vipers and Alley Vipers.
Or do a Python Patrol repaint of the viper/trooper/CG/BAT.
Or do a ninja set, with a Night Creeper, Aleph/Night Creeper Leader, Red Ninja and V2/Joe Storm Shadow.
As for sets 3-5, Imma still support Flint, Jaye, Zartan, Shipwreck, Spirit, Serpentor, Firefly, Mindbender, Stalker, Zarana, Gung Ho, the Twins and the Dreadnok trio of Buzzer, Torch and Ripper are the big, important ones.
Just spitballing opinions. ^-^