I can attest to Kabutops performing well as a Rapid Spinner and lategame cleaner / last-ditch Extremekiller Arceus revenge killer, but it does have issues in the first role. It's biggest flaw is being unable to Spin safely against the Spikers themselves; Ferrothorn obviously OHKOes with Power Whip and Forretress can Gyro Ball for a good chunk or simply Volt Switch out.
As for Cloyster, my mantra is "why Rapid Spin when you can Shell Smash?" Cloyster is not the kind of Pokemon you can slap onto a team. The team needs to be built around Cloyster and giving it that pivotal turn to set up after removing the opponent's priority users / insanely fast Choice Scarfers (like Darkrai fast) / really bulky Water-types. So for such a team setting Cloyster up for that opportunity is pivotal and using Rapid Spin is a waste of that turn in which Cloyster could have instead won the game or torn some holes in the opponent's team. That said, Cloyster is very effective at Rapid Spinning so you can try that if it floats your boat I guess.
As for Spikers: I quite like Spikes Deoxys-A. Yes, you read that correctly. A, not S. the reason for this is because Deoxys-A itself forces switches, and can function perfectly well with just Psycho Boost, Superpower, and coverage move X or ExtremeSpeed. It really puts the opponent in a bad position if you use Spikes as they switch. They're once again caught at the disadvantageous 50/50 position a Deoxys-A with no drops against a slower Pokemon puts a player in, and that situation only gets worse if they switch only for another layer of Spikes to be set, or just let their wall die. And if they switch their Choice Scarfer / priority mon (often the only method they have of coping with Deoxys-A) only for it to dies to Psycho Boost, then they are often in a whole mess of trouble since they likely no longer have anything that can outspeed Deoxys-A.