Clairvoyant is a challenge that can only be gotten before a certain point in the storyline (during Systems Jammed ), as it requires you to bring down the forcefield for the second transmitter before you're asked to do it. If you're going through the first time, then you won't know about it, so you would need to do it on a TVHM playthrough.
You can do it as soon as you enter Concordia the first time and are able to freely explore it. There's a jump pad right in front of the fast travel station that you can use to get to the rooftops, and the forcefield is right next to where you land. If you head straight away from the forcefield, you will see a console and behind that is the switch that shuts it off.
Doin the Robot
Inside of Moxxi's bar is a Claptrap unit named B4R-BOT, who will periodically move to the dance floor to get down with its bad self. Whenever it does this, stand near him and just move back and forth a bit until you get the challenge.
Its a Fair Cop
CU5TM-TP is a Claptrap unit that will roam around Concordia, issuing tickets to whoever breaks the law. There's a few spots where you can break the law, such as a planter near where you first enter Concordia, as well as a dumpster marked as flammable near the statue and Serenity's Waste gate. One last thing you can do is drop a weapon whenever you're near the Claptrap unit.
There are two slot machines in Moxxi's bar that allow you to spend money, which is based on story progression, to spin them. There's many possible outcomes that will grant you prizes, but for this challenge, you need either three Vault Symbols and three Moonstone Cluster symbols. This is entirely random and there's nothing you can do to rig the machines in your favor.