Ogres:
Fanatics, fanatics and more fanatics.
8 in 2000-2250 is generally accepted at tourney in OZ as not too
OTT. if you are putting one in a unit of
NGs, put in 2 instead as the minimum.
Fo NGs, nets are also a great option reducing regular bull attacks to
St 3.
Ogres only have the gnoblar trappers as fanatic releasers so deploy so they can't scout near you.
Bolt throwers. 4 in an army will still allow for other special choices and you should be hitting half the time.
Giants- just avoid the tenderiser armed tyrant. Hell take 2 and run them up the flanks.
As for skaven, can't help wih O&G, not enough experience in that match up.