Stay together. Focus fire.
Good advice in so far as it goes except that's it. So advice that is so general as to be entirely useless. Instead of 'stay together' try instead 'Follow the Atlas DDC' if you want to be real fancy 'Follow the Atlas DDC we are flanking left' . Actually gives people some idea of wtf the plan might be (if there is one).
OK now lets deal with 'focus fire' shall we. In the hurley burley of a brawl it may not be easy to tell who is meant to be focused. Some hint via text would be awesome. Maybe from the already dead team mates? Or whoever was taking charge earlier when they were giving the wonderfully helpful advice? "Kill that ******* splatter-pult" is a target call people can get behind.

And while we're on the subject of good advice. If you are in an assault and you walk round a corner into 3 heavies DO NOT turn around and try to run away. It never helps. Plan a) should be pick one and try to kill it plan B should be die well and carve as big a chunk off them as possible. Same goes if you are a heavy and run into a bunch of mediums. Turning your weakest armor to them and trying to run away when they are faster then you is pretty derp

And here's another one. If your natural inclination is to snipe from round things and then run when people get too close... assault mechs are not for you dude. See running away above.
So if you are one of those people that says 'Stay together. Focus fire' and nothing else please for the love of good come up with something actually useful.Or funny at least. I sometimes start matches by suggesting my team should...
split up
don't focus fire
don't press R
don't hold locks
and at least 2 of you go afk
I mean it's probably going to happen anyway so may as well legitimize it.