What IV for attackers?

Anything from 0 to 100% should do it. As it is an att it make sense to use the ones with good att iv stat, but it is almost the same thing.

For me, at the moment, pokemon level is more important than IV's, because stardust is much more difficult to accumulate than it used to be (no more automatic 5,000 stardust every 21 hours).

I still refuse to save any mon under 82%, and I haven't powered up a mon under 89 since well before the change.
Att IV has gotten a higher considereation.
Since a 100% IV Dragon can still have 400+ higher CP than a 0% one, that can make a difference when attacking a gym or fighting a raid!!!

For long run IV still is the key. As tm can change move set, it doesn't matter what current move set you have. For raid, unless they change something in the future, you only need less than 20 varieties to deal all bosses. So power up some good IV will let you get higher cp mons eventually.

All preference really. Personally, I don't invest in anything less than 91% IV.

With how the game can change, I think powering up and evolving high IV is still a safer bet...

At this point, you can't change IVs so I'd be hesitant to use TMs on low IV mons...even low level mons with high IVs are better IMO...

I found a Machop nest and farmed it till I had 500+ candies...evolved a 95% and got C/CC, took to level 31...

After continued play, you will get more and more candies and will eventually get enough IMO to build a decent team.

My shiny minimum is 71%. Regular mons are 89%.

If I catch something already level 30 depending on the species I may evolve it but not power it up. I have a 65% Tyranitar @3013 cp and a 65% Machop on standby at 955.

Just evolved a 53%Vaporeon with 100 less cp than my 89% one with the same moves at the same level.

the only major issues battling affects now is beating raid bosses. make sure you have teams strong enough to dispatch those high level bosses for when your team is not very large. Otherwise, you can throw anything into a gym and taking down gyms with one mon isn't rare anymore...