I don't believe so.
Predator
For Predator, Shooting Wild is a great skill. Ustanak is so fat, that if you don't get a hit at medium to close range, you're an idiot. Shooting Wild provides you with no disadvantages, and the boost in power. Magnums you pick up from the map do some serious work with shooting wild on.
When playing as Ustanak, you need to use a hit-and-run technique. If the survivors group up on you, the predator becomes the prey. Vital got dropped in like 15 seconds when he was first Ustanak because he kept staying around the survivors.
Don't use the Ustanak's physical attacks. They're terrible, along with his grab claw thing where it shoots out. Just use his shoulder charge to plow through groups, and the close range grab is a guaranteed grab, at very close range, unless they might dodge roll it. Might.
Don't use Ustanak's grenades at close range. When he does the attack, it's so obvious, it's not even funny, so the agents can just casually walk out of the way, avoiding the attack, costing you physical stamina. Use grenades to intimidate. If two agents are down, and you see others going to heal them, I like to use grenades to keep them away, possible dealing slight damage.
Edit:
When you have someone in your hand as Ustanak, throw them at another player. If they're smart, they'll roll out of the way.
If not, they get knocked down, then you can grab them putting them into dying status.
The grab automatically puts anyone into dying status.
The Ustanak roar is great because while it does cost stamina, it shows everyone's position. It's good if you can't locate those last few survivors and you don't want to give them a chance to heal others.
Onslaught
I don't really have tips for this mode, lol it's all pretty much common sense. Use firefighters and barrels to extend your combo and such.
Only thing you have to worry about is the damage mutilplier, which increases with melee kills, going to a maximum of 300%, which you'll need against those large groups
Survivors
Be familiar with weapon spawns, since they really change the tide of battle. One grenade launcher, RPG hit, or grenade launcher hit can **** you over.
Always watch your back, especially when there are players playing as zombies. So also, keep moving, don't stop. You can be fighting a human agent, and a human zombie will grab you from behind, making you lose.
If you're a zombie, staying alive is your priority, but only be a dick to an extent. If you're last alive team member is dying, try and kill them yourself, so you can return to the living. Why? It's better than losing the match!
Well timed attacks with zombies and J'avo can really mess people up. I learned this recently from my friend who has like almost 100 wins in Survivors. You can easily corner someone as a J'avo, and unless they pistol quick-shot you or counter you, they're done.
Never take on more than one person at a time, unless you have a powerful weapon. You won't win, lol trust me. It's not like Gears of War where you can instant-kill people. You'll get double-teamed, and it's over.
Quick-shooting techniques with snipers and shotguns can rape the competition, especially if they don't expect it.
Make use of the turrets on Requiem for War in team versus. Have some dude act as bait, and mow down the dudes chasing him/her.
Make sure you're stocked up on ammo. You won't survive off melee, unless you're really good with Jake or something. Ammo can be dropped by killed zombies.