Could have refers to the ability to do whatever it is.
Would have is more about the intention to do it.
If only I had known about your arrival, I would have come to the station to receive you.
In this example the speaker is saying that if they had known, they would definitely have met the person at the station. If we change it to:
If only I had known about your arrival, I could have come to the station to receive you.
the speaker is only saying that they would have had the ability to be at the station. Whether they would have actually turned up or not is left unstated.
If only he could have explained.
is saying that 'he' was not able to explain. But if we change it to would:
If only he would have explained.
It's still grammatical. It's saying that 'he' had the ability to explain, but chose not to for some unspecified reason.
(I tried to use would in my answer as little as possible, since it's one of the words in question, but I couldn't think of any sensible way to rephrase my sentences.)
The following three sentences mean different things.
If you had come tomorrow, I might have been able to help you.
This sentence is a counterfactual. It means that, because you came today instead of tomorrow, I can't help you. And there is no chance that I can help you if you come back tomorrow—you lost your chance for help by coming on the wrong day. Or maybe you have a deadline; tomorrow is too late.
If you came tomorrow, I might be able to help you.
If you come tomorrow, I might be able to help you.
These both mean that I can't help you today, but if you come tomorrow, there is a chance that I will help you.
The difference between them is in my perception of how likely it is that you will come back tomorrow. If I think it's very unlikely, I would use came. If I think it's very likely, I would use come. And for moderate likelihoods, either tense works fine.
Best Answer
The sentence is correct. Since the sentence has 'should have' followed by a verb the verb should be in the V3 form or the past participle of come which is 'come'. An example could be- You should have stopped your car at the shop and looked outside to see me.