That seems about as good as it gets to me. (I mean, the absolute ideal would be for the imperfect IV to be Attack, but hey, I'm breeding with the Hasty nature under the logic that Greninja's Defense is already crap anyway, so who cares if it goes any lower? It can't really take a super-effective physical attack regardless.)
Personally, since getting the Shiny Charm, I've been deliberately storing all the Froakies I hatch just to see how many eggs I have to go through before getting teh shinyness… So far I've got 8 boxes full. So 240 eggs so far, no luck.
Finally I got one! Hasty Nature, perfect IVs in everything but Attack… Ideally I would have had it be Timid, but hey, that still seems rather perfectly competively viable to me. (EDIT: Oh, and looking it up on an IV calculator, it seems its Attack is either 24 or 25. So still pretty damn solid there too.)
For the record, the shiny one was egg number 305.
And just one day before the European release of ORAS too! You know, maybe I should just transfer this one over to Alpha Sapphire and have it as my designated Water-Pokemon... Or maybe going through the storyline with a Protean Greninja would make me a tad overpowered. I mean, I've already basically decided to play through the game without the Exp. Share to prevent it from being too easy (I'm assuming the Exp. Share is as overpowered there as it is in XY) so maybe giving myself a supremely awesome type-shifting ninja-frog with near perfect stats would kinda undermine that attempt at getting a decent challenge...
Well anyway, TYPE-SHIFTING BLACK AND CRIMSON NINJA-FROG WITH NEAR PERFECT STATS, AT LAST YOU ARE MINE!!!