The only way Squirtle can be seen as 'spiritually replaced' is if Greninja is a water starter and there is a suitable grass starter to replace Ivysaur. Otherwise, no, Greninja is just a hapless sixth gen rep who happens to be a water Pokemon starter in the next game. Greninja and Squirtle fight nothing alike, and if you remove the necessary Pokemon battle representation out of it with the starter trio, the essence of Pokemon being gone with both BATTLES and starer pokemon, then not only is Greninja a poor choice, but he has absolutely no connection with Squirtle whatsoever other than being a Pokemon.
The biggest disappointment with this roster for me will be the essence of Pokemon. Up until this game, Sakurai has done a terrific job with catching elements of Pokemon. He understood the importance of trading in Chrom for Robin, going as far as stating
I can only hope he understands all that Pokemon is missing just by having random Pokemon in place- that the series of Pokemon is so much more than just random Pocket monsters. I think his inclusion of Pomeon Trainer at all shows he knows this.
Ultimately, Sakurai is aware of how important Pokemon is to Nintendo. It got two reps in the first game, two in the second, and four in third. I cannot believe it would only get one this game, and based on a sketch, at that....
It is a MAJOR franchise to Nintendo, and if Mario is getting this much attention, I would be utterly shocked to see Pokemon so ***** slapped.I honestly could see Pokemon getting up to 8 characters without it seeming overboard on a close to 60 character roster.
Personally, I would go with
Pikachu, Lucario, Greninja, Charizard, Sceptile, Mewtwo, Pokemon Trainer, Jigglypuff.
I hope we get some major surprises with Pokemon Trainer. We have been told all characters were taken from scratch, and seen how evident this is in Bowser and Pit. Hopeful for what this means with Pokemon Trainer, beacuse he is such a vital part of Pokemon, and he ushered in the avatar character, which we now have four more of (Mii, Robin, Wii Fit Trainer, Villager). He is my number one most anticipated returning character, and as far as I'm concerned, far more worthy of returning than Snake, Lucas, Wolf, or Ice Climbers, ten fold. Bitter immensely at all these "smash fans" who don't even give him the time to be mentioned.