Prioritizing powering up

Edit: Sorry, i deleted my Posting instead of editing it. I stated:
(1) Jolteon / Lapras
(2) Flareon / Espeon
(3..99) others
(100) Golem

To Golem:

Of course, it is far from being useless. It can be regarded roughly as a rhydon with a negative 50 Stamina-IV. Its only advantage i know is double effectiveness of rock versus fire / flight (Charizard). For any other matchups, it is simply a cool looking weeker Rhydon.

For me, stardust is to valuable for a second best Pokemon. I invest into the best ones. This should explain my priorization.

3
5
4
1
2

I would say:
3
2
1
4
5

In my opinion:
2 (must kill those Blisseys)
3 (Gyaradoses are quite common)
4 (it can already kill Dragonites in a row, but needed to be powered up because of the nerf)
1 (a backup against Blissey)
5 (most useful against Charizard, which isn't really common)

All except Golem, others are efficient attackers for the Big 7

I'd power all of them up to level 30 right away unless I had a Rhydon with rt/se, then I'd probably skip the Golem.

If strapped for stardust (and why would you be with all those great movesets not powered up), I'd power them up depending on local meta. If I was in your situation I would go:

1. Lapras. I still don't have a truly great Dragonite killer. This one would do nicely.
2. Jolteon. That moveset WRECKS Gyarados and Gyarados is everywhere! My second most used attacker after Exeggutor (as Vaporeons are THE most common defenders here).
3. Flareon. Killer moveset. Wrecks Exeggutor but can be used against Snorlax/Blissey as well due to high DPS.
4. Espeon. Strong attacker in general.
5. Golem. Solid, but not really amazing against any common defenders.

Jolteon and Golem first, for the sole reason that most people won't have them prepared for gyms. The only powered up Jolteon I have seen in a gym is mine, and Golem isn't used much because he is inferior to Rhydon on defense.