You could use what we stumbled upon to be useful:
3x5"/4x6" index cards, each named for one of your PCs and as many needed for Monster Group 1, Big Bad Evil Guy(BBEG) #3, etc.
We laminated ours and used dry/wet erase pens to track HP's, Init, and other references(RR mods)
Sort them via Phases that the PCs call out for their actions, then by Init rolls within each, or just forego Phases like most folks and go by INIT rolls in general.
To track Stun, turn the cards to the right from tall-ways and put ticks you cross off when their card comes up in next init order.
Turn Stunned No Parry to the left.
I saw some kind of initiative tracker cards long ago but they don't need to be fancy!
As always, YMMV.
There are even magnetic white board options for cheap out there, too:
https://kataklyzm.files.wordpress.com/2010/04/pzooms1000_500.jpeg