Bowser has very safe kill confirms but I feel like he will be in the top tier area NOT because of his general matchups but because of how he can play around the top tiers in a way that allows him to succeed against them. Some of the top tiers I am mentioning include: Shiek, Fox, Peach, Diddy, Mewtwo Zero Suit, Toon Link, Pikachu, Villager, Luigi, Peach, R.O.B, and Lucas.
At absolute BEST bowser has to make FOUR moves hit, with no rage,in order to kill most of those characters: D-tilt, U-Throw, F-air, B-air, F-smash
So between Bowser's ability to safely rack up damage either through N-Special, Tomahawk Side-B, or grab combos AND Bowsers ability to Safely poke shields with D-Tilt and Jab allow a quite fearsome match to be played in addition to one of the best out of shield options of any character...
we have a very likely contender for a top tier character.
"Bowser has bad recovery"
--So does Rosa-Luma, Diddy, and Marth/Lucina
"Bowser has bad landing options"
--So does Shiek, Mewtwo, (Debatably MetaKnight), Marth/Lucina, and Peach with the only exception being that Peach has a way to subvert her landing option weakness via smart Turnip plays
"Bowser is combo food"
--So is Fox, Cloud, and Ryu
"Bowser has all of those weaknesses combined though"
-- But his heavyweight status makes his combo food weakness a secret strength in the form of rage.
Bowser is indeed a very strong character whom has giant weakneses that stop him from being top 10.
I personally say he's number 13 out of 56 on my tier list.