Should I just show up with the cash? or do I have to bring some forms as well?
Nobody carries cash like that for safety reasons. You should use cashiers check or travel card to carry most of the money and carry few hundred dollars cash.
If you have lot of money to move to Canada, you can move to Canada with few thousand for now and transfer to Canadian bank later online.
If you really have to carry cash, you can declare it and have a good reason. For example, you want to buy a car in cash etc. What border agents might not buy in and then you might face grilling interview.