Leslie's name in Raph's phone: Fluff🐱
Leslie's name in Donnie's phone: cat who is very much not a dog😤 (it's said a lot, so now Donnie has a long contact name).
Leslie's name in Mikey's phone: 😁❣️(he adores her, but I could not come up with one).
Leslie's name in Leo's phone: Mi Hermosa❣️
Leslie's name in Splinter's phone: Blue's girlfriend😁(if you think about it...makes sense).
Leslie's name in April's phone: 🌟Superstar🌟
Leslie's name in Cassandra's phone in the future: You're my hobby😜( they know their contacts and so thus a joke, by what this means, Cass loves Leslie in a friend way and loves hanging out with her).
Leslie's name in Draxum's phone in the future: Dog ears😝(to annoy her).
Leslie's name in Casey Junior's phone in the future: ✊🏻🤛🏻👍( uhhh... yep, meaning you go, up top, good job).