One of the biggest mistakes made in the post Crisis (on Infinite Earths) world, was when there were flashbacks to the Justice League of America with the Atom standing with his fellow members in the Justice Cave or on the Satellite, full-sized in costume.
Atom power was his small size, but, here are a few exceptions to that from the Silver Age with art by Gil Kane.
The Up And Down Dooms Of The Atom
First up is a tall tale from Atom #32
(August-September, 1967) by Gardner Fox
, Gil Kane
and Sid Greene
(with cover by Gil Kane
Here, Ray Palmer is paralyzed by being struck by a beam in a laboratory accident. The accident also gave Ray telepathic abilities, and he contacted his fiancee, lawyer Jean Loring, to activate his shrinking belt....and thus Ray shrank...out of sight.
At submicroscopic size, Ray could move again, but, at that size, he was a giant in a microscopic world, where he has to save a group of farmers (the Palonds) from invaders (The Honds). There, he finds a radiation that cures his problem of moving while full-sized and returns home.
Sometime the smallest guy in the room can make the biggest difference!
Trouble At The Ten-Year Club
The second story, from Atom #11
(February-March, 1964) by Gardner Fox
, Gil Kane
and Murphy Anderson
(with cover by Kane
), does have a human sized Atom (but also shows WHY he shouldn't be!).
Here, scientist Ray Palmer meets with 10 fellow Ivy University graduates from his class, all bringing back an item to the reunion from their current profession, except for Jack Archer, who sends a note saying he will steal the other nine objects.
Archer would have gotten away with the items too, if not for the Mighty Mite, but the Atom had to beat him after he forced the Atom up to normal size (where Archer beat him). Ray knew his Atom costume was invisible at full size, who Jack couldn't have done what Ray thought he did, and found out he was doing it all via hypnosis using the power of Hindu idol. The Atom turned the tables, and used the idol to plant a suggestion in Archer's mind, allowing Ray to capture him.
The Atom NOT being in costume at full size saved the day here for Ray Palmer!
The original Justice League of America
title had a few appearances (the first reprinted in a JLA Giant
) where Atom was larger than his team (making Ray a giant member of the Justice League)....
...but, if you check other appearances, even outside the JLA, like when the JLA members battled the Calculator
, or when Atom was searching for Jean Loring in Super-Team Family
, they show (properly) Atom being Ray Palmer when he was around his teammates in his full size!