Lvl 3 solo

Rhydons and Golems should do better than the vapes, have you tried using them and not dodging at all? Arcanine shouldn't be able to wipe out all 6 of your attackers, so I think not dodging as its merit.

Do not use the dragonite, it's not good enough. Remember super effective is 1.4X now.

I posted last night that damage does in fact go up for each power up on your attacker. My level 38 Pokemon will do significantly more damage than your level 30. IVs also make a difference. A group of 6 level 30 Pokemon doesn't guarantee you a win.

I soloed one yesterday with about 2-3 seconds to spare. I am level 37, and used one maxed (3185) MS/SE Rhydon, one 2613 RT/RB Golem, and the rest Rhydons and Golems in the CP range you listed. So, I'd say my results were consistent with yours.

That was my second attempt; I failed on the first by loading up on hydro pump Vaporeons and Gyaradoses, but the Arcanine had wild charge, so my team took too much damage.

Mud Slap is generally a pretty bad move so from what I've seen, here are the top PURE dpsers into Arcanine/Flareon...Also, phone lag can make it impossible to solo Tier 3 mons. iPhone seems to lag less in general.

Even on GamePress:
Golem RT = 17.78 DPS
Rhydon MS = 15.00 DPS

Golem Rock Throw Stone Edge
Golem Rock Throw Earthquake
Starmie Water Gun Hydro Pump
Omastar Water Gun Hydro Pump
Vaporeon Water Gun Hydro Pump
Feraligatr Water Gun Hydro Pump
Gengar Shadow Claw Shadow Ball
Dragonite Dragon Tail Outrage
Kingler Bubble Water Pulse
Rhydon Mud Slap Stone Edge
Alakazam Confusion Futuresight
Omastar Water Gun Rock Slide
Tyranitar Bite Stone Edge
Dragonite Dragon Tail Hurricane

I found dodging with your highest charge mon helps. If you were 2 seconds away, I extra charge may put him away. I am not sure who is the hardest hitter against Arcanine.

Level 3 solos are TOUGH! It's the most fun part of the game now. I've tried Flareon and Machamp, failed twice. You really need to have the right set of 6 monsters with the right move set.