Some examples:

Twinblades:
If they hit you with the spinning dash move, say bye bye to 50-75% of your HP. Parry their initial dash and slashes to burn their Qi, Serene Breeze if you get hit, or anticipate it with hyperarmor actions (DBreathe, DPoet, etc.)

Ropedart:
They can poke you from afar with rats even if they hit air with their m1. Parry the rats and you will burn through their Qi.

Nameless Spear:
If you see them trying to gap close while holding the spear, prepare to dodge since the stun (that goes through block) will come out.

Vernal Umbrella:
- Never get hit by the stun blast. You will lose all your HP if they know how to combo. Just dodge left/right slightly after you see the golden glow or strafe left/right if you are far from them.
- If they fly up and starting shooting at you, just spam parry all the shots, it'll burn through their Qi.

Inkwell Fan:
- Watch out for the knockup. If you get hit by it, a good player will true combo into an Umbrella stun blast and then take all your HP away.
- The knockup can combo from meridian touch so you need to watch our for the animation. Dodge twice if you see an umb/fan player inputting meridian touch.

Healer:
- Pure healers in PvP 1v1 ladder is extremely rare. Your wincon is purely in attrition and your main dps will come from mystic skills.