Dr. Tornado is amazing. It has a lot of priority and if you use it offstage on recovering opponents you can kill them as early as 70%. Also worth exploring is his down B custom that gives him a lot of height to improve your recovery.
His up B now works more like Luigi's, with a strong hit at the start of the attack and a weaker hit throughout (the strong hit doesn't pack as much punch as Luigi's but the weak hit isn't as weak either). It's also a great quick kill option, especially out of shield.
His up smash now works more like Mario's, mean less combo potential but more kill power. His forward smash and down smash are still pretty fast kill options. Sadly, his forward air is his least reliable kill move now because it doesn't deal nearly as much knockback and you have to sweet spot it.
Compared to Melee, pills do less damage and have slightly more lag while firing them, but they're still a good option for stage control. His Super Sheet is basically the same but he doesn't stall when using it in the air anymore, he just keeps falling at the same rate. His reverse sex kick is back but because you don't carry momentum out of a dash jump you can't karate kick into opponents like you could.