i was at big stadium battling
my darmanitan(fire/zen mode) v wootwoot(flying)
i first use flamethrower and wootwoot got burned
then it used extrasensory and roost
afterwards I used earthquake on it(dont ask why) and it had no effect-no suprises there
darmanitan got his HP in half and triggered its zen mode(still no suprise)
the second time I used earthquake it did damage!
i used it 3-4 times and did fair amount of damage
on my next turn it said it had no effect after that it did damage again I did this until all PP of earthquake was done( btw wootwoot still kept using roost)
i finally finished it with fire fang
how did this happen I thought ground moves have no effect on flying types