This trophy is titled "This Is Important..." and it's for hearing Noel say "Hands off the panda!" 100 times. In order to do this, you must be facing Litchi as Noel first and foremost. Secondly, you'll have to use her special move in which she shoots at her foe which is initiated by flicking the right stick to the right. If done correctly, she'll fire a mid-range shot and you'll hear her say the phrase.
If there's a full-screen gap you shouldn't hit her and you can easily knock this trophy out in one round in a matter of a few minutes.