HP is really the most important stat because it gives more room for error ( due to high latency / lag, you'll find yourself missing dodges more than you'd like ). After HP, it really comes down to either your dodging skills ( you could beat entire gyms with a single pokemon... even when your attacks are not very effective ) or picking the right type for the fight, or ideally, both.
As long as your primary attack is "the right one" ( e.g.: Water Gun for Water types ), don't fuss about the rest much..
PS: Don't believe every ranking list or DPS chart you see ( e.g.: Golduck actually has slightly higher DPS than Vaporeon with Water Gun... he lacks Aqua Tail, but in all honesty, is that marginally increased DPS worth getting hit 1-2 times for free? Not for me... I'd rather dodge the hell out of everything and use only Water Gun... it saves you a bunch of potions and keeps you in fights much longer ).