Here are my observations;
They can all be dramatic sometimes.
They all like pizza and have a sweet tooth.
They all like the mall, although Lincoln likes it least and Lori and Leni like it most.
Lisa, Lily, and Lincoln are all smart, though Lisa is by far the smartest.
Lucy and Lisa are both stoic.
Lincoln and Lucy both believe in ghosts.
Lola and Lori are both bossy.
Leni and Lana are both animal lovers.
Lori, Lana, and Lisa are all techies.
Lori and Lincoln both like video games (although Lincoln likes them more by far).
Lori, Leni, and Lily all like to talk on the phone.
Lincoln and Lisa are both analytical and both believe in aliens.
Lola, Lori, and Leni all like fashion.
Lily and Lincoln both like taking their clothes off and they're both schemers (as evidenced by "Any Given Sundae").
Lynn, Lincoln, and Lana all have some gross interests (Lynn has her Dutch ovens, Lincoln has his peanut butter and sauerkraut, and Lana has all her gross stuff).
Leni, Luna, Luan, and Lucy are all artists in a way.
Lynn and Lori both like sports (although the only sport Lori likes is golf).
They're all very loyal to one another.