I am sure most people won't consider Luffy to be badass because of his goofy nature and childlike attitude....but he is one of the edgy characters once he becomes serious and has many badass moments...however I will post most of the badass moments of Luffy as they are subtle....
1) Emphasizing to Nami about what it means to go against pirates by putting the life on the line
2) Putting hat on Nami and destroying the room that Nami stayed in arlong park
3) Smiling while he was about to be executed by Buggy in Logue town..
4) Emphasizing the significance of pirate flag in chopper arc...
5) Hitting Vivi and emphasized the main issue...
6) Asking Usopp to shoot the government flag...
7) Introducing himself to WB...
8) Facing three admirals....
9) Arriving at Saboady post-TS....
10) Punching a Celestal dragon
11) G4...
12) Challenging BigMom
13) Chapter 949.....
Some of the badass dialogues...
"No matter how hard or impossible it is, never lose sight of your goal."
"I've set myself to become the King of Pirates... and if I die trying... then at least I tried!"
"Dying is not repaying a debt! That is not what he saved you for! Only weak men would die after someone spared their lives!"
"We are NOT asking him where the treasure is hidden! We're not even asking him whether there IS any treasure or not!! I'm not sure, but... ...everybody set out to sea, risking their lives to search for it! If you ask this old man anything about it here and now, then I'll quit being a pirate! I don't want to go on a boring adventure like that!"
"If you don't take risks, you can't create a future."
"You want to keep everyone from dying? That's naive. It's war. People die."
"I don't want to conquer anything. I just think the guy with the most freedom in this whole ocean... is the Pirate King!"
"You came without fear. Don't have any regrets, no matter what happens. This is the duel you wanted."
"If you hurt somebody... or if somebody hurts you, the same red blood will be shed."
"I am going to save you even if it kills me."
“Power isn’t determined by your size, but the size of your heart and dreams!”
let me know if I miss something....