DC official Twitter asked
Most of the answers are either non sidekick or hasn't been a sidekick for a long time and already a main character of their own book, like Wally (big Wally not small Wally)
DC official Superman twitter answered Jon, and the comments immediately jumped in that apparently DC themselves admitted that he's just a sidekick
At the very least the DC official twitter is kind enough to question if Harley and Nightwing count
Then there's one reply to a vote of Jaime Reyes saying he's a main character with sidekick energy
So what's your answer?