Finally submitting something. These are some concept sketches of three gym leaders of the Ziito region. I've removed Doctor Tarr from his place as the 8th leader in favor of his younger brother, a biker known as TarPit. I've also redesigned Sheila significantly, and added Helga- the ice leader- as well.
Some brief descriptions...
TarPit is the most powerful gym leader of the Ziito region, and the leader of an infamous gang of bikers known as the Black Mamboas. His gym is actually a biker bar, and his girlfriend, Vicky, is the bartender. Despite his intimidating appearance and demeanor, he is actually incredibly loyal to any trainers who defeat him. In fact, in the player's final encounter with Doctor Tarr, TarPit saves the player from being attacked by Tarr's Vamprayer. As a poison specialist, TarPit's team consists of Aeroconda, Drakatoa, Plutroleum, Anthroxide, and Tetanusaur.
Sheila is the fifth gym leader of Ziito, and she specializes in fighting types. In addition to her duties as a gym leader, she is a yoga instructor devoted mother of three. She claims to have gotten into yoga in an effort to get healthier, and at the beginning of every battle she says to her challenger 'I look good for a mother of three, don't I?" Sheila's team consists of Yoguarundi, Ravadger, and Tazmaniakk.
Helga is the sixth gym leader. She is a world-renowned opera singer, and it is said that her voice causes Pokemon to weep with joy. Helga's gym is the theater in which she performs, and the battle takes place during an opera. Her commands are sung to her Pokemon. As an ice type specialist, Helga's team consists of Owlvalanch, Polarine, Predaparda, and Queenieve.
Their names come from tar pit (of course), sheila (slang for 'woman'), and hail.
References used include Wattson's BW2 sprite, Giovanni's Pokemon Special artwork, the D/P battle girl sprite, Clair's Sugimori art, Lenora's BW sprite, and Bertha's Sugimori art.