Darkest Dungeon II

First of all you need the three listed characters in your party at the same time (keep in mind the Duelist is only found in DLC). Then you'll need to build a team composition that at least has all 3 riposting, if not necessarily emphasizing it. Emphasizing it is a good strategy though because it punishes the enemy for attacking you. Here are recommendations for each of the 3 characters:

Man-at-Arms: The vanguard path gives nice buffs for riposte attacks. Use the Retribution skill to gain riposte tokens and force the enemies to target him, ensuring a riposte attempt.

- Highwayman: Rogue is the path that most favors the riposte. You'll need Duelist's Advance and/or Take Aim skills to get riposte tokens. The rogue class modifies duelist's advance to move forward 2 spaces instead of 1 each time, just keep that in mind for positioning.

Duelist: This character has some wild path/skill combos, but if you're going for ripostes I recommend the base wanderer path. Use Meditation and Feint to generate your riposte tokens (Preparation will buff your riposte attacks). If you can pick up the Dark Lanthorn trinket for her, it will further buff ripostes.

Get into a fight with something tanky (like cultists) so that you have enough time to set up and successfully activate ripostes on all 3 characters. Once one of them scores a riposte, have them use buff skills to keep enemies alive long enough for the other two to score theirs.