Then your rival got a the fire pokemon, so you should atleast get a poliwag since it is good against your rival
and when, IF you use water stone for fully evolve it becomes a good fighter type too.
a flying type would be good for the 2nd gym so a pidgey or spearow.
if you not have beaten first gym which is in VIolet city, go down to the grassy area at route 32 and get a mareep which is electrical and good against first gym.
and maybe a gastly from the sprout tower?:)
for me that always is a good beginning, then I change my team a little bit later in the game, when i need better Pokemon