Is it possible to parry all melee attacks in PvP?

I'm practicing my parrying and notice, in PvP, that it's harder to parry the heavier weapons when wielded in two hands. Especially Ultra Greatswords and Maces I haven't yet been able to parry in PvP. Maybe I need to continue working on my timing, but it made me wonder:

Dark Souls 3 PvP: Is it possible to parry all melee attacks?

If not, which are the known melee weapons (or ways of attacking) that inhibit the opponent's option to parry?

• Whips cannot be parried.
• Jumping attacks from all weapons cannot be parried.
• Certain weapon skills cannot be parried. Generally, if it doesn't make sense to parry them they can't be (for example, Stomp).
• Two-handed great hammers, greataxes, ultra greatswords and curved greatsword generally cannot be parried.

This reddit post has a full list if you want to know specific skills and weapons.