Thunder Jolt is a very useful move in many circumstances, and has been in pretty much every Smash game.
Using it to keep people of the edge is undisputedly one of its many utilities. Bear in mind, when using Thunder Jolt, you should always start it up in the air. Using it on the ground gives you large amounts of lag, and since the move is easy to shield or even dodge, you are really setting yourself up for a punish. I haven't tested it in this game, but in Brawl (and the other games, I believe), Thunder Jolt would do 9% if you hit with it when it was airborne rather than on the ground, when it would do around 5%. Even if are using it to edgeguard, remember that it's essential to jump before you hit the B button. The best way of doing this is to input jump at the same time or a moment before B. If I'm not wrong, that has the least lag. Doing it at the top of a full or short hop will leave Pikachu still in his animation frames when he hits the ground again.