This one is pretty easy. Near the entrance to each of the three wings there's a friendly critter that you can pick up. You'll have to clear a little of the trash to find them. Three people pick up the critter. Then when you start the fight with Hivemend, the critters will appear and 'evolve'. Kill the evolved critters, kill the boss, done.
There are two obelisks on the sides of the room. The black projectile that a single person soaks bounces in the direction that you face. You have to bounce the projection on top of the obelisk to destroy it. The achievement is to break both obelisks, which you can do in two black phases.
The big danger here is that everyone goes to help with the achievement mechanic, and forgets about the other mechanics. On our first try we had several people die because no one was near the boss to soak the other mechanic which requires you to split damage.
Here everyone needs to pet the dog. You need to pet him one at a time, so we just had one person call someone every few seconds. Here's a simple macro for healers (who may not be targeting the boss):
Pretty easy, about the only issue is that you might kill him too fast for everyone to pet him. There's always someone who doesn't hear their name and you have to call them again, which slows everything down. Also, try to do all the petting in the first two phases. Extending the last phase is a pain.
Here you need to get two tantrum phases within 60 seconds. Drest'agar does a tantrum at 100 energy. Each tentacle you kill gives him 20 energy. Kill 4 tentacles, wait for a second set of tentacles to spawn so that there are at least 6 active. Then burn down all the tentacles. Pretty easy.
This one was a little difficult. You need to kill 10 bloods within 3 seconds. What we did was during the first intermission phase we just let all the bloods come out. People being targeted just ran in circles around the center. We had to wait until 15 bloods were released, before everyone ran into the center and unleashed AoE. Healers popped their big cooldowns to survive. We had all the DPS use the AoE laser Azerite essence.
We ended up waiting for 15 bloods because you have wait for them to actually reach the center. So with 15 out, we had 12 dragged to the center. We still lost half the DPS in the resulting explosion, but the remaining raid was enough to finish the fight on Normal.