>>54185406https://gamepress.gg/pokemongo/attackers-tier-listS and A tier are what you generally want.
Keep all your 15 Attack Shadow Pokemon, they might be useful later.
During now event times like now, just accumulate Stardust so when you do get something worth powering up, you can.
One last thing, start adding local people so when you get lucky trades they can send you some legendaries that will have baseline 12/12/12 stats.