To wish people a pleasant stay
is a hope that hosts typically express when guests/clients arrive. It's what you expect to hear from a receptionist when you check into a hotel. It looks ahead.
When the guests come to settle the bill at the end of their stay, the receptionist may well say:
I hope you had a pleasant stay
This looks back on the period when the guests were staying at the hotel.
It's wrong to say:
I wish you had a pleasant stay
because it confuses the future and the past - and it's not idiomatic.
It's possible to write:
I wish you had better manners
but it's never idiomatic to write:
I wish you have (anything)
Instead, you would say:
I hope you have/had
Wishes are unrealizable conditionals, so we backshift the tense of the verb. can is backshifted to could, will to would, and present simple meet is backshifted to simple past met. be is an exception because it has a proper subjunctive: am/are/is backshift to were.
You mention guidelines about action words for future actions, but the word now in examples a and b locates the sentences in the present, so these guidelines don't apply. Furthermore, these guidelines explain what you should do, but they don't explain why you should do it.
I believe that it is much more effective to go back to first principles and make a complete sentence that expresses exactly your wish as it can happen or is/will be happening, then backshift:
I am eating that cheesecake
I wish I were eating that cheesecake.
I can eat that cheesecake
I wish I could eat that cheesecake
My father will let me borrow the car
I wish my father would let me borrow the car
Note that eat is an action word, but the first two examples relate to the present so the "action verb" rule doesn't apply. The first example does not require could and the second example does. Working this way, you can see why could is necessary- because can expresses ability / permission, and can -> could. The third example is about a future event, so will -> would.
You are right that a) and c) are correct. To find out what's wrong with b) and d), remove the backshifts and see what you get:
b) I meet her now.
d) I meet her more often.
b) doesn't make sense because meet is present simple, and we don't use present simple for current events- we use present continuous. To find the correct way of talking about now, change that sentence to present continuous and backshift it:
b) I am meeting her now
b) I wish I were meeting her now.
d) doesn't make sense because more often requires some reference level. If you talk about capability, there is an impled reference level:
d) I can see her more often [than I do]
d) I wish I could see her more often [than I do]
Best Answer
First things first:
"I wish the bus would have stopped here." (This is not grammatically correct in English although it occurs about as frequently as the use of "was" as the past subjunctive of "to be" when "were" is the correct form.)
It should read:
"I wish the bus had stopped here." ("had stopped" is the past perfect subjunctive.)
Now for the rest:
"I wish the bus would stop here." ("would" replaces the present subjunctive herein: "It is my wish that the bus stop here." Because if the bus [should] stop here, it will cut time off my trip.)
"I wish the bus stopped here." ("stopped" is the past subjunctive of "to stop" herein: "It is my wish that the bus stopped here." Because if the bus stopped here, it would cut time off my trip.)
Both examples are relatively close to the same meaning; however, the first example ("would stop") is used when I want it to happen or insist that it happen and it's possible that it may happen one day, whereas the second one is my stating a simple wish that does not happen now and I know probably either cannot or will not ever happen. "I wish the bus stopped here (but I am pretty sure that it never will stop here)."
"I wish you would just have a good time." (You aren't having a good time and it's ruining my vacation!)
"I wish you had a good time [playing sports]." (You do not have a good time doing whatever, but I wish it were not so.)
"I wish you would be quiet." (Shut your mouth! Your ruining everything!)
"I wish you were quiet." (It's impossible for you to shut your mouth, but hey, I can wish, can't I?)
Other exemplars:
"I wish Mr. Smith taught English." (I know that Mr. Smith will probably never teach English, but hey, I can wish!)
"I wish Mr. Smith would teach English." (I just want Mr. Smith to teach English and I know he could teach it if he wanted to.)
"I wish Mr. Smith had taught English [when I was in school]." (Mr. Smith didn't teach English when I was in school, but I wish (now) that (back then) he had taught it.)