Raikou Counter

Don't bother with the Golem or Nidoking.

Because Ground-Types currently have really low DPS moves, high DPS generalists help you to get those extra premier balls in Raikou raids. (This isn't the case for survivability, what I mean is if you have a large enough group to survive, with your team, probably about 5 people)

Use those two Dragonite, provided they are all Dragon-type moves. If you're willing to power up your Mewtwo, that may be a good option as well. I would suggest putting them in slot #1 or #2 before Raikou builds up too much charge. Because they take Neutral damage, these options will also build charge quickly. The other 4 Pokemon I would leave as Rhydons or Donphans, though I would keep the Donphan last since it doesn't hit quite as hard.

Also using a basic simulation (I'm new to PokeBattler) it looks like your level 30 Rhydon fares better than your max Donphan anyways:

Start with your 2 dragons assuming they are DT/O. They have better DPS than the rhydons. Then 4 Rhydons and you are good to go. If you happen to power M2 he can come in as well.

Don’t bother powering up more Rhydons; the ones you have will suffice. I made that mistake just before Raikou and didn’t need them. Agree with others that your Dnites can round out your team.

2 dragonites

I suggest placing a grass attacker (or whatever high DPS generalist) in the first slot. Fill everything else with ground counters like Rhydon.

By the time Raikou left North America, I'd settled on a squad of six Rhydon as counters. The would last almost the whole 300 seconds, and I usually got good personal damage bonuses. Three were "wonders" that I put some investment in. Three were wild Rhynhorn catches that were already level 30, had meh IV, but I evolved anyway.

I tried to sub-in the usual suspects, but this seemed to be the squad that worked the best.