Season 5 opens with Leslie floundering in Indiana as Pawnee’s newest City Council member while Ben is in Washington, D.C., working on a congressional reelection campaign. “The perceived importance of what they’re each doing” puts a strain on the relationship, says Scott. “That, and Ben is surrounded by hot brunettes in power suits.”
Now that Leslie Knope is a city councilor, she'll be getting a new office. But don't worry, she's not really moving away — seriously, it's, like, around the corner from her Parks Department pals. But she's still a little lonely. So she comes up with an ingenious way to get Tommy Fresh to come hang out with her.
In her quest to pass her first bill, she'll need to persuade an old-as-dirt councilman to vote in her favor — but he'd rather just make out with her. Naturally, Leslie Knope won't stand for those shenanigans, so he ends up in the hospital. Oops, lost that vote. 
April takes on a lot of new responsibilities, in which we will see her mature. 
April will return to Pawnee in episode 5
Ben is having a hard time fitting in with his cabal of young, male interns. You would think April, who will be working with him in D.C., would stick up for him, but she's actually the cause of many of his problems -- in particular, the drawings she's making of him with a stick up a certain orifice.
Tom will crash Ron's car, and be in major trouble.
He will start a new business. Aziz Ansari says "That one will go a little bit better because he learned so much from the mistakes that he made with Entertainment 720, of which there were many".
There's an arc that starts around Episode 5 for Tom where he's trying to start a new business but he's grown up a bit and has learned from his mistakes in the past so it's about him trying to turn over a new leaf and take what he thinks is actually a good idea for once and turn it into a legitimate business