100% iv Rhydon

Rock Smash is a bad quick move. Since you have a 91.1% MS/EQ maxed out, just keep this one as a prestige mon.

With Rock Smash as a fighting type it will still do okay against Snorlax, but the lack of STAB means it will be less versatile...

Megahorn is okay, not awful by any means but again lack of STAB means it doesn't inflict as much damage as EQ/SE.

Keep it to max it out when you dont know what else to do with your dust

I have a 100% with the same moveset -_-

I power up all usable 100s. Just my preference. I wouldn't do just for countering snorlax.

Mud Slap and Rock Smash do equal damage to Snorlaxes since STAB and SE are both the same multiplier (1.25x) and both moves have the same base damage.

However, Mud Slap is better when Rock Smash isn't SE, because you'd still keep STAB, plus you'd be SE against types that you'd want to be using Rhydon against, because Rhydon will also have resistance to those types e.g. Poison and Electric and Fire.

The 41/45 IV Rhydon is far better because it's moveset is stronger, which makes a much bigger impact in battle than 4 IV points. You'd be better off using that against a Snorlax too, Earthquake increases your overall damage output more than Stone Edge, despite Stone Edge having higher DPS.

Megahorn sucks, basically weaker Stone Edge. No STAB and no useful type advantage because the types it's strong against, you wouldn't use a Rhydon for.

Rhydon's are a dime a dozen right now but useful as meat to drop in gyms because of their high CPs. I have not powered any of them but I would if I had a 100% with that move set.