Originally, Alvida was a very obese and ugly woman. 
The Sube Sube no Mi makes Alvida very slippery and, aside from the cowboy hat she wears, Alvida looks totally different from her original form, now dressed in a bikini top and wears a furcoat like a cape. She also wears a tight, capri-length pair of pants with stripes and her blouse is usually seen tied around her waist. Most people that see her actually fall in love with her, as seen in Loguetown.
She sees herself as the most beautiful lady in all of the seas; if someone disagrees, she will smash the offender with her iron mace. She imprisoned Koby to be her cabin boy after he boarded her ship by accident. Disliking filth and laziness, her crew was forced to clean the entire deck, if there is even a hint of dust she will once again smash the offender with her club. People used to say she was the most beautiful woman in the world to avoid being hit by her club, these days they really mean it. (Even though Hancock and the Mermaid Princess have also been called the most beautiful women in the world.)
AlliesAlvida at first traveled with Buggy, though only because they have a common person they wish to find (Luffy). She, however, did not seem to tolerate Buggy and his crews constant noise making and asked his crew to not be so noisy. However, she didn't hesitate to abandon him when the crew met a dead end in their quest to free Buggy.
EnemiesSince Luffy was the first man to defeat her, Alvida has become quite infatuated with him; he doesn't seem to quite understand those feelings. She showed little disappointment when Buggy tried to kill him during the Loguetown arc.
She is the prime enemy of Koby, who has not forgotten the years of hard labor and abuse she put him through. He had boldly stated it was pirates like her that he wished to arrest when he declared his actions to her.