I took some notes about my observations from the demo:
-QAC is gone (this should go without saying)
-QA seems to have more lag if you QA into the ground
-QA doesn't seem to go as far as before
-His bthrow doesn't seem to send you back as far, though it does seem to send the opponent upwards more
-His uair works similar to the way it did before except that it has significantly more knockback
-His bair has less knockback, but seems to have less landing lag
-Tjolt is exactly the same
- Thunder is at least slightly faster
-His costumes are exactly the same as his Brawl ones: normal Pikachu, orange Pikachu with Red's hat, slightly greenish Pikachu with a green headband, and slightly bluish Pikachu with blue goggles. (this is obviously very important)
Predictions (I know it's early for this, but it doesn't hurt): Juggling won't be easy because his uair has more knockback. Playing aggressively will be more difficult without QAC, plus QA has more lag if you accidentally hit a platform or the ground with it. He seems very suited to a campy playstyle. Considering lots of other characters got buffed and Pikachu seems to have been nerfed in tons of ways, and is capable of slightly less than what Japan players did with him in Brawl, I predict him to be low tier.
Considering attacks seem to have slightly more hit stun and bthrow sends the opponent higher and not as far back, I wonder if a bthrow>bair combo might work better in this game. Though, the thrower also seems to experience more lag after throwing, so this might not work because of that.
Battlefield could be a more difficult stage for him without QAC to move around quickly and easily. Juggling and sharking don't seem like they'll do him much good since it could send the opponent too far to follow up with another attack. Thunder seems slightly faster, though, so it could be useful here.