On a temporary basis? No, which is why that particular greninja (and its trainer, for that matter) are of great interest to the pokémonology community. The two of them may represent the birth of a revolutionary way to utilize the bond between trainer and pokémon, and that in turn may change the way we view our relationships with our partners.
On a permanent basis, however, some pokémon do start to resemble their trainers (or vice versa) over time, but this is a superficial change that naturally happens when two friends spend enough time with one another. This most notably happens with eevee, not only because it happens quickly (within a few months of being with a new trainer) but also because the phenomenon is tied to its ability to adapt on a genetic level to its environment.
…and before anyone says anything concerning my bias towards eevee, I assure you I just find them cute and scientifically interesting. I’m not that narcissistic, I swear.