BioShock 2 Remastered

The Bonus trials are not a requirement for this achievement.

In order to get an A ranking:

Before you begin make sure you hack all machines. Including the Health station, even if you never use it, the splicers often go to heal and instead will be poisoned.

Rather than standing right beside your Little Sister (essentially drawing them to her) try keeping distance but making sure you always have her in full view. This way the attention of the splicers is split in two.

The moment the Little Sister screams quickly get to her before she loses any of her gathering bonus. If the gathering bonus drops on the earlier trials you probably wont get an A but the later ones you get at little leeway.

The Simon Wales Trials most people struggle with. The best way to get an A. Is stand away from the Little Sister and near to the Vending Machine. On trial 1- use your Decoy and then Blast them with the Launcher. Make sure you keep on buying grenades, I barely used my drill or telekinesis.

Trial 3 Stand near to the vending machine, continually cast Cyclone trap around the Little Sister. Finish them off with the machine gun. Never take your eye off her. Cast at least three traps around her and they should never get to her. If you run out of ammo use incinearate until you get to the machine.

Folly of Dionysus 3 - with no money or weapon it may sound daunting. But is actually really simple if you used Decoy during the campaign. Every time Decoy 3 is attacked you are given health and eve. You also have the Fountain of Youth perk (health/eve restored when in water) Make sure you you always have a target dummy and use cyclone. I stood in the water near the health station facing the girl. Cast a cyclone trap behind you and all around the girl.

When enemies gather around the decoy chain lightning them with Electro Bolt. Finish off stragglers with Incinerate.

Thought I'd add another technique for Simon Wales' Church Trial 1 - achieving an A+ with it first time, and repeating it a second time - if you're struggling with cooper101183's method of using the Grenade Launcher.

Essentially, all you do is keep a decoy next to the large central pillar in the middle of the room on the ground floor, on the same side of the pillar as the Little Sister. Splicers will keep jumping down from the bridge, and immediately attack the decoy. You can then bash them with your Drill. If they start shooting from a distance, take cover behind the pillar, and shift the decoy a bit to the left, right, or a bit closer towards the Little Sister, so that those shooting will target the decoy. As it's the Decoy 2 Plasmid, the Splicers will have their damage reflected back onto them. Occasionally, Splicers will come from behind the alter, but these too should focus on the decoy. For the Brute Splicers, feel free to use your Grenade Launcher. But for the most part, I just bashed and drilled their backs with the Drill. The key part is making sure to refresh the decoy as frequently as you need to (refresh it when the Splicers lose interest). If you see a Splicer not going towards the decoy, it's safest to just deploy another one if you aren't sure you can take them down from where you are.

I often found that Splicers would run off to the Health Station (which was naturally hacked earlier, so it killed them when they used it) - including the Brute Splicers. This way, you only need to go to the Vending Machine to buy any necessary Eve, Health, or possibly Fuel - which are all cheaper than the Frag Grenades - and you're essentially next to the Little Sister, just in case a Splicer happens to get close.

You'll have to judge when it's safe to leave your decoy by the pillar, and get over to the Vending Machine, but you can sort of feel when you're in-between Splicer attacks. You have your Drill Dash too (RT + B), which is great for moving around quickly, or close the distance between you and a Splicer. As with all of the Trials, you have to be a bit adaptable, to account for different spawn locations.