Injustice 2
75 Achievements
153-209h
I Love You, I Hate You
Harley must defeat Joker with the final hit coming from Go Night Night
0.5%
How to unlock the I Love You, I Hate You achievement in Injustice 2 - Definitive Guide
Obviously you're going to play as Harley Quinn and pick Joker as you opponent.
This is one of Harley's combo moves.
It's done by hitting , +, + You want to do it with your opponent at around 15 percent health. Less than that and you'll defeat your opponent before she completes the combo. If done correctly Harley will knock the Joker down to the ground and smash his head with a baseball bat a few times.
As pointed out in the comments you can use in place of +. Easier than trying to hitting 2 buttons simultaneously.
Please adjust.
As a fellow noob, I also need to point out not to press ANYTHING, specifically X+A again at the end of the combo. I was pressing X+A twice and it wasn't executing.
Select any mode you like, select Harley as your main character and Joker as your rival. Select any map and start the match.
Once the match starts, keep hitting your rival until he has around 5% of health left in his red bar. At this point, using Harley stay close to your rival and perform the combo , + , + (having your rival to the right). Once your rival is defeated with the last hit of this combo, the match will end showing the trophy in the screen.
Video: https://www.youtube.com/watch?v=tNqoxxqcJlw. (Credits: HarryNinetyFour)
A bit tricky. You need to make sure Joker doesn't die within the first two hits of the combo. He needs to be laying on the ground and getting his head bashed in with the baseball bat.
The move is: , +,+.
We choose Harley, the opponent of the Joker.
The combo is done using , + , + . Execute when the enemy has ~15%.
https://youtu.be/DZ6ceF12f14
The combination will be Triangle, Forward + , Square + (left side of the battle. If you are on the right, then everything is the same, but instead of Forward + will be Left + ). You need to do it quickly, the trophy is quite difficult/inconvenient.
After changing the button, I did it 3 times during the battle, before (by default) I never did it once.
Video to help: https://www.youtube.com/watch?v=tNqoxxqcJlw
You need to defeat the Joker when he has 10-15% HP. I advise you to do it on easy difficulty level in battle with AI.