Don't give up on the Latias raids @Efferlunt, it took me 7 tries to get one. I've now done 16 raids and caught 5. A friend caught her 1st 9 and has done another 17 raids and now has 10! :o She really is a bugger to catch.
@CollyWombles, I agree with the others, don't waste stardust on rats and pigeons, don't power up anything until you're at least level 25, maybe even level 30, and then only 'Mon that are over 90%. I power up sparingly, the only ones being my 100% Feraligatr, now a 2604CP level 37 critter, Dragonite, my best Gary, my best Golem and my best Tyranitar.
I treat Stardust like gold (or its digital equivalent) as it's finite. You only get it from catches or raids, it's the one thing you can't buy in the shop. Long may that continue.
On my quest towards Mew I will complete task 6/8 today by evolving another Gary and doing 10 raids. I have no idea what tasks await as I haven't searched. I just know (from Prof. Willow) that it's invisible. Now I hope to learn how to 'see' it.