Supergirl and Brainiac Five joined the Legion of Super-Heroes at the same time. Power Girl joined the Justice Society of America when Per Degaton's temporal clone battled them. Sparks flew, with Earth-One's Girl of Steel suspicious as Five was the alleged descendant of her cousin's old enemy... Earth-Two's Maid of Might just plain didn't care for the arrogant genius spliced from a moment of his predecessors' timelines. Who could blame them? At times, Querl Dox... as this Brainiac was actually named... had a tormented psyche that plagued his teammates with dreams of grandeur. At one point, he threatened his universe and caused the temporary insanity of teammate Matter-Eater Lad. But he redeemed himself of this unfortunate attributes, and was a stalwart member of the 30th century Legion, even coming up with various devices such as their flight rings. Although he did accidentally create one of their greatest nemesis, Computo. Still, it ultimately became subservient, so all turned out well. And maybe that's why Kara of Krypton-One was so enamored by this troubled yet tenacious teen of the future.
No such qualities were found in Degation, any Degaton for that matter. The first tried to conquer ancient history and set up a modern day rule at least ten years into his future before the Justice Society overturned his plans. The second Degaton tried to use the crisis of Pearl Harbor and World War II to his advantage, although then the All-Star Squadron was formed to defeat him. The third Degaton had a rematch with the All-Stars, the Society as well as Earth-One's Justice League..even ruling forty years later... until the heroes defeated him once more causing that timeline to cease to exist. The forth Degaton was left without the means to time travel, and after a stint among the Injustice Society versus his old foes, he ended up an old man. When Brain Wave revived him, the pair faced a Justice Society now having a Kara of Krypton-Two. And even though Degaton like Brainiac could come up with a nifty force field and other gadgets, his intellect was no match for the enthusiasm that was the Supermen's lady cousins.