Now this may sound like advertisement for an addon, but rest assured Im not affiliated with it in any way.
TLDR I just discovered an addon that greatly improves and expands the options for macros, with one of many neat features being the option to check if a given ability is known/usable by your character. In other words you can once again make macros that include multiple pvp talents, and not have to worry about dragging them to your action bars everytime you change a talent.
The addon in question is called M6
A lil guide for those who need help:
The macro command to check if abilities are known by your character is simply known:spellid. You can find the spell ID for abilities by looking it up on wowhead and clicking on “links” in the top right corner.
As an example, the macro for either explo trap OR spider sting would be:
#showtooltip
/stopcasting
/cast [known:236776] Hi-Explosive Trap
/cast [known:202914] Spider Sting
The addon also has lots of other nice features, with conditionals like zone, type of instance (do one thing inside arena, another thing if not in arena) etc. As a disc you could use the following macro to dispel party1 if inside arena, and target party3 if not in arena:
#showtooltip Purify
/stopcasting [instance:arena]
/cast [instance:arena,@party1,help] Purify
/cast [instance:arena,@party1,harm] Dispel Magic
/target [noinstance:arena] party3