Guess I'm surprised you didn't learn this or get the answer to your question in your Firearms Courses -
Oz
Strange comment Oz. Very few PAL courses are going to go down to shot size and shell recommendations for two specific upland species. As a poster above said, this site is for asking questions and sharing information.
As for shells, 2 3/4" only. You actually want very light loads for upland, I see a 1oz load of 6 shot as perfect in 12 gauge. Actually, I use a 1oz load of steel 4 shot as I use non-toxic shot for everything, and with steel being slightly lighter, I up the shot size.
For standard shells, some of the best grouse shells you could buy with lead shot are Winchester AA's in the extra-lite 1oz load of 8 shot. For pheasant, I'd be saying 6 shot or bigger, but the same 1oz load, 1 1/8th oz at most (most pheasants probably fall to even less shot out of 20 gauges and 28 gauges).
Just a note on pheasant hunting, there's a good deal to it. Grouse are easy, but pheasant, at least where I'm from usually requires a bird dog and some travelling, plus a lot of time. It's is about the most fun you can have in the field, however.