I never thought Murkrow's perish song is so OP. In my first play through I met a lvl 75 garchomp and the guy Solaris wasn't even humiliated
I'm fortunate first attack of garchomp missed my murkrow and was able to use perish song.
I'm not sure if it's a bug but I can fight a trainer multiple times in the building in Opal Ward. Name is Physic Silva and has pokemon Mawile, Xatu, Sneasel. I keep beating him and gain 1,200 money.