Letraset's grasp of superhero lore was somewhat dodgy, as you've already seen from the 1966 pink Batman. Things weren't much better ten years later; you can have fun picking out the errors, but the most obvious is probably "Superman and Superwoman Foil Space Shot Raid".
In the upper part of this scan, featuring a rusty Aquaman, you can see how the transfer sheets were tucked into slits in the background card, & then stapled into place for extra security.
In the lower part of it, you can see the back of the staple — wow! — & the transfer sheet poking out on each side through the back of the card:
As you'll be able to read for yourself when you examine the scans, this range came with a promotional offer: if you rub down twelve of the Bat Signal logos which appear on each transfer sheet onto a piece of paper & send it to Letraset, they'll send you a Super Action Heroes set. Not sure if it's a random set, or if you can choose — but you'd better hurry up! These offers don't last forever, you know.
Number 5 is the odd one out; on the back of that one, the offer specifies a BATMAN Super Action Heroes set. My guess is that they reprinted the cards when they realised they would run out of Batman!
(Reprinting transfer sheets was expensive & difficult at this time; reprinting the backing cards, pretty straightforward.)
Pezing very kindly sent us from Germany some photos of (among other useful things) a sealed counter box of Super Friends:
GK234/4 — Number 1: Death Express.
Batman saves Batgirl from rails of express train.
We've arranged the twelve sets over twelve pages, so just click on one of these images to go to the right page for the title you're interested in.
Number 2
Number 3
Number 4
Number 5
Number 6
Number 7
Number 8
Number 9
Number 10
Number 11
Number 12