Sand Power Dory sounds great in a trick room until you realize that you could also be using Sand Power Gigalith. He's bulkier, has the same attack stat, gets Stone edge, doesn't get outrun by Bronzong and Reuniclus, and probably isn't countered by Gliscor.
While adamant Dory is outsped by certain +2 pokemon that jolly dory isn't, I would still would use adamant. Pokemon such as Kingdra need at least two turns to beat adamant excadrill. Pokemon like Terakion and Landorus will be doing it in one turn regardless of nature.
While gravity is seen as a gimmick, has anyone else tried running Dory alongside gravity support? It makes the pokemon who would otherwise try to counter you if you were healthy mere fodder. The rotom forms can no longer touch you. Bronzong is no longer switching in. Skarmory can't even try to phase. Balloon magnezone, heatran, and terakion are all smacked down. I personally used a mew and one other pokemon to set up gravity while running a utility role and the results were always positive. Usually, my opponents would avoid switching in their gravity crippled Dory counter and lose around 2-3 pokemon before gravity ended. But it still forces them into a corner. Obviously you don't want to end up doing this if your opponent has their own Dory, for reasons I need not mention.