I have hard time believing that
Dragalge is unranked. This mon does really well in this meta, deserving C+ or even higher.
Since metagross ban everything went well for this mon. Gengar, nihilego, and other posion types went down in usage, leaving much room for Tspikes support. Volcarona is not used as much so you don't have to be afraid about Z-Psychic. Most spammed mons like Zaptos, Koko, ZardY, Bulu, Keldeo are beaten by it. Rain is more popular so another thing able to come on specs hydro is needed. Dragalge is suprisingly good right now.
Tspikes are godlike right now. Well played can poison Mew, Fini, Tangrowth and bring them down to the point the cannot wall anything (tangrowth takes almost from
scarf keldeo if rocks and tspikes are up). Since half of meta has bad matchup against dragalge it is to lay them down.
And now some replays showing how much support gives and how good dragalge is:
http://replay.pokemonshowdown.com/gen7ou-598473284
Thanks to Tspikes Heracross is able to murder half of enemy's team.
http://replay.pokemonshowdown.com/gen7ou-598468323
After ground types are dead, dragalge almost deals with rest of rain team.
http://replay.pokemonshowdown.com/gen7ou-598453890
Same deal. Excadrill dies, Tyranitar dies and suddenly nothing can deal damage to Dragalge.
This mon is way too solid to be unranked.