Speaking of things outclassed by Raikou... (I said for the sole fact that I knew it would piss you off. I realize that Raichu has its own niche.)
Anyway, I was going to say Manectric. While all of its stats are worse than Raikou's, and it can't run a Calm Mind set, but everyone know it gets the wonderful move called Switcheroo. And also unlike Raikou, it actually has a somewhat decent movepool, and when these things are combined, it can run a Choice set much better than Raikou. I would prefer Specs over Scarf personally.
You slime!
But I digress. Specs Manetric huh?
Besides Switcharoo, I would assume you would Manetric over Raikou because of overheat.
The age old question of just how useful surprise/novelty sets are. Lose something, potential gains= risk.
That's not novelty, that's just a very bad idea. Milotic doesn't have decent attack or a good physical movepool to take advantage of it, and it's not like it'll help it against any of its counters.
Manectric will have to get a lot of game-changing surprise Switcheroos to justify the fact that Raikou undermines its existence statistically. I've considered Raichu, but its only decent stat is speed, which rests at a modest base 100.
If you want an Electric type that does a great deal of damage or, furthermore, sweeps, you might as well use Raikou. When using the others, just make sure their unique "advantages" are important enough of an asset to the entire team that would warrant using them over the best special sweeper in UU.
It could still work because many OU Pokemon have "little brothers" in UU, meaning a Pokemon with the same purpose and/or typing. For example, a Pokemon meant to counter Gyarados could counter Feraligatr, a Pokemon meant to counter Infernape could counter Blaziken, a Pokemon meant to counter Jolteon could counter Raikou, etc.
Two sets on my fav. sweeper of my UU team: Clefable
Clefable @ Toxic Orb
Belly Drum
Facade
Fire Punch
Softboiled
and
Clefable @ Life Orb
Belly Drum
Double Edge
Fire Punch
Softboiled
The best thing about clefable is it's natural bulk and the ability magic guard. (No damage from LO or Toxic Orb)
The reason I add the Facade set is because Toxic Orb prevents you from being paralyzed which will end your sweep with clefable.