I haven't had the issue with observers much, but I do agree with that. I just use overload, lance, throw, or concussive shots. That usually stabilizes them long enough and shuts their * lasers. The breachers are just annoying as hell. Nullifiers are easy to take down. You just have to be fully behind a wall or keep moving (treat it like a banshee ball). If you're in the open and fighting a nullifier, just keep moving around. Get in close, make it pull it's shields down, then back up.
Nullifiers are easy just use hover attack with a sniper or if you are close enough X-5 with an electrical beam upgrade.
As for a swarm of breachers Nova takes them down quickly.
