I sometimes wonder why people are so aggressive when it comes to other people using nonstandard stuff. (in this game)
The one thing I agree with all these dumbasses that are disregarding the OP is the fact golduck doesnt really counter excadrill, kabutops etc etc. However, I believe that was just bad wording and he meant countering weather in general, not the mons in particular, which it does.
So, for the OP. Test Golduck and see if it works for you. If it doesnt, try something else, if it does, just ignore everyone in here cause honestly, I have given up in the creativity of this game long ago.