OK here a idea, What if the Classic Mega Man also had Double Soul just like his EXE counter-part? I'm going with all the Double Souls that appears in Battle Network 4 and 5. However some will be remove, like Colonel, Maddy, Number and Thunder Souls do to not have a Classic counter-part. So the Souls I will show a each chapter will be...
From Mega Man 1,
Roll Soul, Proto Soul, Guts Soul and Fire Soul.
From Mega Man 2,
Metal Soul and Wood Soul.
From Mega Man 3,
Magnet Soul and Shadow Soul.
From Mega Man 4,
Just Toad Soul.
From Mega Man 5,
Gyro Soul and Napalm Soul.
From Mega Man 6,
Wind Soul, Tomahawk Soul and Knight Soul
From Mega Man 7,
Just Junk Soul.
From Mega Man 8,
Aqua(or Spout)Soul and Search Soul.
If there any made up Soul forms from the other Mega Man games, please let me know and I'll try to write it. Free free to make up your own looks for Classic Mega Man when using Double Soul. And if you want me to add in the Soul from Battle Network 6, I will. Just remember I may have to remove some since they do not have a Classic counter-part.