My 'best' Feraligatrs to come out of community day for raids were: (had quite bad luck in terms of IV)
CP1964: 15ATT / 1DEF / 14HP
SHINY 2259: 11ATT / 0DEF / 12HP
I managed to get one at 1480 for Great League PvP with Bite/Hydro Cannon/Ice Beam so thats sorted but i really wanted a couple for raids due to hydro cannon making it more than viable water raid attacker.
I know these dont look great stats and are around 67% and 50% however im looking to use these in raids, does this low defence actually make them even better for raids seeing as low DEF stat charges a charge move quicker?
the lower defense = better DPS is a myth. Your blastoise are good raid attackers, but I wouldn't worry about IV's too much, they are good as attack is really all that matters, and you still have a good few months to stock up for mudkip when it gets a CD (I highly doubt niantic'd cut off the hoenn starters from the moves)
for PvP, blastoise is better than feraligatr in both great and ultra leagues.
Due to the way damage is calculated you will never see a noticeable difference in positive energy gain from a lower defense IV. Not to mention being so low on the IV scale means you're less likely to hit the final defensive breakpoint of a given matchup, resulting in you fainting before getting to utilize the extra energy.
tl;dr the low defense IV strat is a meme, people who cling to it probably have buyer's remorse about heavily investing in something with sub-par IVs.
