They are still legal tender, but subject to rounding. Most merchants don't want to handle them and will not accept them so they no longer circulate. Banks are obliged to accept them for deposit and submit them for recycling.
It's a token, don't understand why you are asking for grading in the Canadian coin section. Listed as ON225 in the compendium of Canadian municipal trade tokens. 25,500 were struck. Not worth grading, one recently sold on eBay for about three bucks, can be found in the 3 for $10 bin at LCS A cool keeper so far away from home.
1973 dollars are likely the most common spectacularly toned dollars of all. The toning is caused by off-gassing of the original packaging material. The doubling is flat and shelf like mechanical doubling which brings no premium. Many dealers have bins of these toned '73 dollars for less than $20 each. It's a beautiful and interesting coin, a keeper, not worth the trouble of selling.
Nickels are not clad, they are struck on cupro-nickel alloy planchets. Containing 75% copper they can be quite reactive, toning/staining such as seen on your coin is not unusual.