I wish you could. vs I wish you would.

[Eileen]

i learnd about" i wish "

i was wondering ..

i wish (i or we) could
i wish (you or he or she or it) would

are they correct?

can i say " i wish you could have gone with us that day" ?

or i should say " i wish you would have gone with us that day"

do i have to say only" would " after "i wish you "?

[Cerberus™]

All of your sentences are possible. There is no link between I/we and could, nor is there any between you/he/she/it and would in the way you suggest. You can use could and would with all persons; they just have different meanings. This subject is quite complicated, perhaps you could look up a page on the grammar of auxiliary verbs on the Internet.