I don't even have a clue how to get the one for not killing any of Ustanak's winged b***he's in the caves. I have most of the other ones in the campaign. Also the no damage one for mercenaries is going to be a massive pain if not total luck.
Funnily enough I'm attempting the Jake Ch2 Oko one tonight solo. It's easy in co-op if you have a partner willing to kill all the bugs for you while you just watch on the sidelines but I don't relish doing it alone.
As for Mercs no damage, I got this last week playing as Sherry EX, Catacombs. Stay well aware of who's around you, take the zombies out from a distance (especially lantern carriers) and if it looks like your combo is about to expire then give up on it rather than attempt something heroic.
Save flash grenades for bloodshots to target them easier.
You can get the medal with a B rank (I had 96,000 points) so it's easily possible with just one or two decent combos.
Hope that helps. As for unlocking a title, I don't think so but I could be wrong. --- 'What did you say?! Insects' life doesn't compare to human lives!'
I don't even have a clue how to get the one for not killing any of Ustanak's winged b***he's in the caves.
Mining Cave 1 - Allow the first Oko to turn and fly along the walkway and follow behind it. When it turns and sees the characters, rush to the end of the walkway and fall off the ledge to the left then quickly hide in the red container below to avoid Ustanak.
Mining Cave 2 - Fire a handgun shot once to alert Ustanak then hide in the red container. When Ustanak leaves, get out of the dumpster and fire another shot to alert him then hide inside the red container again. Ustanak will leave the area at that time. Follow the first Oko all the way to the end of the cave tunnel while behind it. It will turn and see your character at the end, so quickly fall down the ledge and then run toward the metal container at the end of the cave tunnel then use the partner assist command to push it.
Mining Cave 3 - Walk over to the far right side of the railing and find the ladder. Wait for the Oko in the corridors to move out of the way then drop and run to the corridor directly ahead. An Oko will see your character eventually, so run to the stairs and quickly open the door.