She's already got advantage, both from how good the speech was and from the entire party standing there looking intimidating on deck.
The dice think otherwise though
Intimidation against the bullies: 1d20 2
Skill is +4, but that's not going to help that much...
Edit: Oh, I just re-read the advantage rules and seems I can roll two dice and chose the better one. It's been a while since I last played, sorry . If I misunderstood the rules ignore the second roll.
Intimidation against the bullies, Advantage Re-Roll: 1d20 9
Not great, but better