>>57140296He's great, he's a wall that puts opposing pokemon in range of revenge kills, and also shuts Sabrina down if you have two of him on the field.
The main downside is, as you said a free kill. But that tends to happen when your opponent sets up faster than you. It buys you time in the early game, protects your main hitters, does chips damage, has an easy retreat with Leaf, and if Drudd gets KO'd, it's just 1 point. Not bad for all the utility you get.