Arcanine: As a Lead? Arcanine is a little lacking in power to produce the necessary KO's that you have geared him to do. In this case I suggest Scarf Moltres or Scarf Typhlosion. Here are the sets:
Moltres @ Choice Scarf - Modest
EVs: 40 Def / 252 SpA / 216 Spe
~ Overheat
~ Air Slash
~ U-Turn
~ Will-O-Wisp
Overheat and Air Slash, completely unresisted in UU, coming off a 383 Special Attack stat is painful to say the least. Also, with enough speed to outspeed every other common lead (Yanmega is BL), Moltres can put a nice dent in your opponent's lead or their entire team if kept alive long enough while Stealth Rock isn't on the field. U-Turn for scouting, WoW for a bit of status if your opponent is bound to switch something in that doesn't like it.
Typhlosion @ Choice Scarf - Mild/Rash
EVs: 144 Atk / 252 SpA / 112 Spe
~ Eruption
~ Focus Punch
~ Overheat / Will-O-Wisp
~ Earthquake / Hidden Power Ice
Eruption, one of the most powerful fire attacks in the game (well, at full health, but you WILL be striking first most of the time), coupled with excellent coverage and surprise in Focus Punch and EQ/HP Ice, Typhlosion is an excellent lead killer. Like Moltres, takes a hit from SR, and like Moltres, can dish out the pain.
If you are looking at a different lead that isn't at all similar to Arcanine, try the Lead Gallade from the analysis, which should work in UU pretty well just as it did in OU (for a short time). Make sure you omit either Taunt or Destiny Bond for Stone Edge, as it is more important in UU to hit the flying types that cause you issues. However, if you want Gallade to be a suicide lead, then try your hand at Destiny Bond, but hopefully you are good at mind games.
A sweeping Milotic? Milotic has nothing BUT it's bulk making it useful. It's sweeping abilities and utility are lackluster, so as a wall or sponge, it is better off. Although a lesser used option, you should try a RestTalk Milotic since you have no status sponge.
Milotic @ Leftovers - Modest / Calm / Bold
EVs: 252 HP / 240 Def / 16 SpA
~ Surf
~ Rest
~ Sleep Talk
~ Ice Beam / Toxic
As the analysis says, if you are using Ice Beam, stick with Modest or Bold, if you want the defense from Marvel Scale's activation to skyrocket, use Bold. If you want to use Toxic, use Calm or Bold, depending on what Milotic's job is.
I noticed from her on that your team has three Pokemon that take SE damage from Ice, which can be especially bad since every bulky water is going to be using it. I will get back to this later though.
Rhyperior: In UU, without Hippowdon or Tyranitar giving it a needed Special Defense boost, Rhyperior isn't going very far as a phazer. In fact, your Arcanine would do significantly better as a phazer in this case. You scoffed about how many Pokemon do laughable damage to it, but what about threats such as Donphan, Slowbro, Azumarill, Claydol, Sceptile, and Weezing that will easily survive any attack and KO back with their STAB moves respectively. Not only this, but they outspeed Rhyperior. Many of the Fighting types will be switching in on Rock Blast or get phazed in by Roar and threaten a KO with Close Combats. Rhyperior needs some life insurance to stay alive in the dangerous UU metagame. Subperior and RockPolish Rhyperior would be better alternatives, although I suggest you go generic and use Donphan. You would have Rapid Spin to rid the field of entry hazards that would hurt Honchkrow and Arcanine, as well as a decent physical sponge, and a Stealth Rock user of your own to replace Rhyperior.
Venusaur: Yes, Venusaur can finally make better use of a Swords Dance or physical set with Power Whip, but your Venusaur has some pretty bad type coverage, and with only Milotic and Arcanine to take the elemental Ice and Fire attacks aimed at Venusaur (and others of your team), Venusaur would look better with a special set with HP Rock. I can see the Standard Leech Seed / Sleep Powder / Energy Ball / Sludge Bomb set working to a better appeal for your team. The SubGrowth might also work.
Honchkrow: with an uneven special and physical spectrum on your team, I suggest Honchkrow to be mixed, a Nasty Plot / Sucker Punch mix. Btw, Brave Bird did very little to help Honchkrow, not making any necessary KO's come out of it that Drill Peck didn't already accomplish. A 125 Base Attack just makes every neutral attack sting.
Overall, your team is just a bit too fragile, with few oppurtunities to actually get most of your Pokemon in. I suggest using either bulkier sets in general, or changing out a few of your members to bulkier Pokemon.