I am looking for suggestions. I was hoping for something with a group of teenagers gaining superpowers. I would prefer something medium in length. Whether it's complete or on-going doesn't matter. I'm ok with anything except historical and hentai.

Ratman

Um, assuming you aren't precisely looking for "superheroes," but rather for "people with superpowers," Aphorism and the Law of Ueki both fits.

Otherwise, if you were looking for actual superheroes, the only thing I can think of right now is Tiger & Bunny (SAKAKIBARA Mizuki), and I would actually recommend the anime, rather than the manga.

tokyo mew mew

Ratman is fairly good with a nice art style. I would not be surprised if it gets an anime soon.

Banana Gecko!!
[img]http://www.nodiatis.com/pub/19.jpg[/img]
[img]http://www.wizards.com/magic/images/whatcolor_isblack.jpg[/img][B]

Superhero
Zetman
Ratman
Psyren (sorta)

Not superhero
Yamada-kun to 7-nin no Majo
The breaker
Mx0
Taboo-Tattoo

Second Zetman and would like to add Akumetsu

"The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown"

Alive

Magic Knight Rayearth
Iris Zero Gakuen Alice (kinda)
Katekyo Hitman Reborn! (perfectly fits, but it's a long-runner)

[img]https://dreamuniverse.files.wordpress.com/2014/10/gilgamesh1.jpg[/img]