In general, which pokemon would you consider powering up?

None until after the gym update.

Mostly power up favorite mon for attackers / off meta defenders. I grew up with the main series games so I invested in a few of my favorites that were outside the top tier.

Arcanine, Sandslash, Nidoking, Primeape, and Tentacruel are a few I invested in for attacking or niche defender before gen 2

Wow. A lot to consider. A good amount of those is a definite "no". If I had to put it in s top three I would say

1. Machamp
2. Exeggutor
3. Eeveelutions (more specifically Vape>Jolteon>Flareon)

I've only powered up an Exeggutor and a Venusaur so far.

This is to deal with the large amounts of Vaporeon and Rhydon's in my area. I also have 2 maxed Lapras (pre nerf) which I use for Dragonites in gyms. That pretty much covers all I need.

I evolved a Lvl 25 Machamp (got C/CC) and plan to evolve a hatched (lvl 20) Machop if there is some event,

If it gets C/DP, I will take it to Level 30.

With these, every gym is possible to knock out fairly easily...

Need more Machamps for Blissey mostly.

For attacking, AS OF NOW, invest in nothing beyond 2K CP (sometimes 1.5 is enough), I only invest in direct counters, no "generalist", that means, no dragonite, rhydon, Gyarados, Snorlax or Tyranitar. I prefer to get good 2 same type attacks pokemon that directly counter a "top defender".

For defense, just snorlax (ZH/x) or blissey, if you don't have one of those, Gyarados, Rhydon, Dragonite and Tyranitar are fair game just for gym placement, at least until the upcomming gym rework.

Other than that, I power up 100% IV pokemon as trophies regardless of movesets because... why not?

Just the ones I like the most or are cool for me.

For example can't wait to get a dragon scale to get my Kingdra. Really love this guy and have a nice IV Horsea ready for that. Once i get this scale gonna power up Kingdra all the way.

I'd also go for Alakazam since always did like him but not sure if gonna power up all the way like Kingdra.

Also considering Crobat but probably won.t do it.

Espeon and Umbreon already powered up them all I could, specially I like Espeon.

Raichu if it was stronger I'd power up him too.

Also planning to get a Meganium as soon as i get the candies and a good chikorita specimen to go with. Always loved him when used to play gold/silver/crystal version on the GB. So bad his max CP is rly low.

Those would be my priorities, maybe add SKarmory and Gengar and maybe missing some guy.

As you see I would go for the pokemons I like the most, not the ones with higher CP or better skills in game. Of course and as mentioned before, even if I love some pokemon I won't power up him all the way if it's as bad as Raichu is on game.

I am looking for a decent C/CC Heracross to max him out. I caught many of them and have candies enough but no decent ivs yet (im from Brazil).

My current list that I would spend dust on as attackers, outside of what you listed at the top:
Exeggutor with Solar Beam
Venusaur with Solar Beam
Golem with Rock Throw/Stone Edge
Machamp with both fighting moves (if I had one)
Jolteon (I like Discharge)
Vaporean (one maxed with Aqua Tail)
Muk (because I like him, I feed him when I can)

I have powered and would recommend powering, the following to level 30 but no further:
- Machamp (Attacking moveset)
- Exeggcutor (any moveset)
- Venusaur (Attacking moveset)
- Various Eevolutions, but not Umbreon atm (Attacking movesets)
- Donphan (Defensive moveset)
- Cloyster (Attacking moveset)
- Ampharos (Defensive moveset)
- Steelix (Defensive moveset)
- Szicor (Attacking moveset)
- Arcanine (Attacking moveset)
- Alakazam (Attacking moveset)
- Gengar (Attacking moveset)
- Charizard (Attacking moveset)
- Golem (Attacking moveset)
- Muk (Attack or defensive... just because it's rare/cool)

• Lapras (Not right now. Candies are too precious and the gym rebalancing might make it a good defender again, which in that case I'd recommend powering up a defensive one, or if they keep it how it is I'd recommend powering up an offensive one)

I like having a ton of different type options, not because I need them but because it keeps the game interesting.

exeggutor conf/solarbeam
espeon confusion/future sight
cloyster only to just over 2000cp for dragonite
arcanine he is more robust then flareon and can reliably get through more defenders (for me)

other quality evolutions (a quality jolteon to make sure it can get through 2-3 garys, flareon as part of my blissey parade funnily enough my best vape is only 89% and i can't bring myself to spend dust on it)

if i had a quality machamp i would but I don't. I do have a quality focus blast alakazam that is supposed to be ok against blissey and am thinking about it.

II think espeon is under rated as a defender if it has a psybeam, it might be a glass canon but it has a hell of a canon may need to power up an appropriate attacker, like an appropriate t rex if i am lucky with my evolution or umbrion, these also might come in handy when legionaries come out.

For the most part I only power up defenders, except for a few power ups to get a prestiger where I want him.

Right now, I am only powering up Blissey and Snorlax On Blissey, I am limited by my own lever. On Snorlax, I'm limited on candy. I have 700K dust that is waiting for the right time to use.

To attack gyms, from your list, i would choose:

Machamp (great against Blissey)
Exeggcutor (great against Vaporeon)
Donphan (with a moveset like Counter and Heavy Slam against Blissey and Tyranitar)
Cloyster (really great against Dragonite)
Ampharos (great CP and HP, kinda better than Jolteon but still not effectively better than a big grass pokemon in battles)
Scizor (Good CP and a great steel pokemon, which makes him a good counter against a lot of other pokemon types)
Wigglytuff (Good against Dragonite and ... Snorlax?)
Alakazam (Full Damage)
Gengar (Full Damage)
Golem (Great attacker, even though a lot of weaknesses)
Tangela (Low hp/defense, but still a great alternative against Vaporeon)