I'm at about ~1550 right now, not sure if I can go much higher in time so I guess I'll just go in depth about my team and what I've found so far.
There are actually a lot of options in the UU tier here, starting with Gligar and going down to most things lower than that on the speed tier list. The biggest threat really is that all of the good responses to Bulky Water types are basically gone. In order to beat them, I decided to start with a combo of Lanturn and entry hazards. Both Froslass and Quilfish are available to Spike. Both are perfectly viable, and Quilfish is a neat Heracross check, but I go with Froslass because of Taunt and high Speed. Fast Taunt helps me against Mew, Azelf, and the like, especially since I don't really want Rocks up for this team.
Lanturn is okay but it's not as great as I had hoped. Its main problem is that it can't hurt ANYTHING at all. It's useful for Waters, Raikou, and Tornadus in particular. I put Scald / Discharge / IB / Toxic on it, with the idea that it is always going to threaten some kind of status on something. Toxic helps against stuff like Suicune, forcing it to Rest earlier. Still don't have much that can beat it, but it helps.
I added Rhyperior for Rocks and also to help against random threats. Rhyperior shouldn't be below 30 in usage. It's really that simple. I can get Rocks up with it fairly easily and generally pose an offensive threat to anything.
Rounding out the defensive core is Rotom-H. Actually the last Pokemon on my team, what I didn't realize is just how useful Specs Rotom is. I would actually argue it is at least on par with Chandelure. For one thing, it is a flawless Raikou switch in. Resists BoltBeam, HP Grass, Signal Beam. Seriously, Raikou can't do shit to it. Substitute can be a problem, so I'm considering running something (HP Ground? idk) over Trick on it, but usually I can threaten it out somehow anyway. Another plus is Levitate. It can come in on anything Gligar normally runs for example and immediately present an offensive threat to the team.
My offensive threat #1 is Specs Tinted Lens Yanmega. I alternate between this and Froslass for lead, because the SR weak is a tremendous problem, but also because most teams don't have anything that can really take a Bug Buzz. Zapdos is the most common answer who takes 30-40% from it, but is even bigger Rotom fodder than Raikou, plus it doesn't have Rocks so I can potentially bring Yanmega in on Gligar or Claydol or whatever is Rocking for another go. It is also a Heracross check with the 4x resist to both of his STAB moves and Air Slash in my back pocket.
Unfortunately Yanmega exposes a big weakness in this format's restrictions: Absolutely no viable Spinners. Claydol is dog shit, and the next best option is fucking Hitmonlee. I decided not to bother and to introduce another frail sweeper instead of making a slower bulky team: Speed Boost Sharpedo. What a fucking boss. One Protect and it beats any Scarfer except Flygon (lol). I bring this in late game, maybe on a Volt Switch from Rotom or after a death, and it's like Moxie Heracross except with boosting Speed. You can take out a lot with its moveset, and it's almost always faster anyway. Psychic immunity is really really handy against a Mew or something - you come in on the Psychic, Protect on the Aura Sphere, and then Crunch for the KO.
Overall this team has been really fun and actually more successful than my old UU team. Lemme know if anyone else in this challenge wants help or suggestions.