IV Threshold

IMO 86.7%+ ivs if im going to MAX HIM OUT. In the other hand if i really need a pokemon on my fleet and he have at least 13 attack iv, a good level and at least 75% ivs i power it up to level 30.

My guidelines are a little ambiguous.
I don't even consider holding onto any mon less than 82IV. Exception is if it is the only one of it's kind that I have or it is rare. E.G. I have a 64IV Dnite with DT/O, and it is the only DT/O that I have. Caught her at level 28, powered her to 30 and stopped.
I don't power up anything above level 30 unless it is 89IV or higher, AND it has a use in the raid system.
I have not powered up Gengar or Scizor, because I have 5 Golem that are all level 20 - 24 and I want them powered before I go for any others.

1. Due to raids and TMs I became an even bigger IV snob then I was before; below 96% I wouldnt even consider investing dust into anything.
2. I prefer attackers with a wide field of usage. I think 2 Dragonites with Outrage, 1 with Hurricane, 1 Tyra with SE, 2 with C and 2 Machamps should be everyone's goal. The next highest priority are specialists that solve multiple problems like grass Eggy, Rock Golem, Vape, Alakazam.
   Mons like Scizor or Gengar that have many ok but only one great matchup don't really feel like they are worth the dust to me.

1. I don't power up any that are below 82% overall (the best in-game appraisal). But any top-tier mon (Gamepress rating of 8.5 or higher as a guideline) within that range (82-100) are fair game. If I focused only one 100% mon, then I would have only four: Dragonite (which I have maxed out), Flareon, Nidoqueen, and a Raichu. I've always favored moveset over IVs so long as they received the 'amazing' appraisal. Of course, that was before we had the chance for TMs.
   Edit: I misread the original question a bit. So to clarify: So far, I have maxed out only my 100% Dragonite. The rest I take only to level 30 (or slightly higher if I miscount my power ups). The stardust/candy cost is simply too great to justify the small gains. I might change my mind if I'm able to build up my reserves and have taken all of my specialists at least to 30.)
2. I haven't as of yet. Up until the last update, I had been focusing on the best coverage mon. For example, I have 2 Rhydon, 2 Golem, 2 Exeggutors, 2 Snorlax all at or slightly above level 30. I have some great IV specialists (Gengar, Alakazam, Scizor) at level 20 that will be powered up as soon as I get my stardust reserves built back up. That is, unless I get lucky and catch a high IV, high level one in the wild.

For easy to get pokemon (common, uncommon that nest, hatch) I wouldn't power up anything below 91%. I have 96% versions of most of them by now.
For rare pokemon 91% threshold would be ideal... but I was a bit more permissive before the update.

96% IV is my minimum (I cheat using third party maps that shows IV)