Scarfed Knock Off/Earthquake Krookodile will be very effective in RU. But of course, you need to have Hazards support, at least SR and 1 spikes. Have at least two walls in your team and make the opponent switch and take some switch-in damage. When all else is said and done, whip out Krookodile and sweep. Start with something that's low on HP and doesn't resist Knock Off. After you get to +2, almost nothing in the tier can stop it. Krookodile has the bulk to take the unboosted attacks of other Scarfers.
Delphox is a great SubCM user. You can have Sub/CM/Flamethrower/Grass Knot, but you miss out on Dragon and Fire types. Granted, there is only a few Dragons in RU and Fire types can't take a lot of switches because of SR.
Honchkrow stays the same, only more effective in a lower tier. Substitute/Sucker Punch/Brave Bird/Heat Wave can break through teams quite easily, if you play it right.
And I don't think Aggron is moving out of RU. Only Aggronite will be banned in RU. Aggron is too weak to too many commonly used types.