Jellicent is actually a very common pokemon on sand teams that checks keldeo very well. It can beat heatran as well, so... For choice scarfers that beat Keldeo, how about Latios? Adding to that, scarf Keldeo won't sweep teams, as being locked into a move is not good for something that intends to sweep. If it is locked into Secret sword, a lot of things beat it including Landorus both formes, Thundurus, Dragonite, Salamence, the list goes on.
Yeah. I run Jellicent on mine. And I agree Scarf Keldo has some coverage issues more than I like. I prefer CM Keldo partially because of that