It's sad how the leaks are making the Smash speculation die out in most places. It sucks how Incineroar might be the most hated character due to be announced last much like Wolf was back in Brawl. On the bright side I'm glad Incineroar can be used in the upcoming Ultra Spooky Cup for Ultra Sun and Moon.
The most "hated" of the final newcomers was ROB (and to a lesser extent Toon Link), not Wolf. Wolf pretty much was only dumped on by Krystal fans for "stealing her spot". Krystal fans believed that she was a shoe-in due to a leak where Krystal's voice actress said she was reprising her role as Krystal in Brawl, and due to a misinterpretation from a statement by Sakurai that he was specifically selecting newcomers that were female (it was from a statement by Sakurai where he explained why he added Zero Suit Samus: the reasons he gave were that he wanted to give the popular Metroid series another playable character and he wanted to add another female character to the roster). Wolf was just as popularly requested as Krystal was during the pre-Brawl days, so the anger about his inclusion was mitigated aside from the Krystal fans.
ROB on the otherhand was a retro character whom had barely any requests, and a character whom many had thought was de-confirmed due to being shown as an enemy in the Subspace Emissary enemy update. Many believed that ROB had "stolen" a slot from a far more worthy character since very few people had asked for him.
With Toon Link, he was popularly requested, however, the Smash Bros. fanbase still disdained the idea of clones, and thus Toon Link got a lot of flak. Some of it was from bitter Midna or Midna & Wolf Link fans though. However, a lot of the sour grapes about Toon Link was the fact that he was a clone especially when a lot of his supporters believed he had a lot of stuff he had unique to himself that would separate him from regular Link (such as the Deku Leaf, Skull Hammer, and Grappling Hook).
Incineroar being deemed the "odd man out" among the newcomers for Ultimate's roster would simply be a throwback to the very first game for the Nintendo 64. All of the characters that were newcomers to that game were icons for their respective franchises or series, with the exception of Jigglypuff.
With Ultimate, Ridley, K. Rool, Inkling, Simon Belmont, and Isabelle are all titans (Inkling and Isabelle being by far the most popular Nintendo characters created during the 2010's). Even the echoes (Daisy, Richter, Chrom, Dark Samus, and the leaked Ken) are all icons for their respective franchises.
Incineroar finds himself not only as the odd man out among the non-echo newcomers, but even amongst the echoes as well. Incineroar is not even the most popular or even the second most popular choice among "core" Smash Bros. fans for a Generation 7 representative. Decidueye and Mimikyu were the names thrown around the most as to who was the most fitting representative for Sun/Moon.
Incineroar is the Jigglypuff for a new generation. It amazes me that nearly 20 years later, people are still salty about Jigglypuff's inclusion. Incineroar might at least have the benefit of bringing a fighting game arche-type (a wrestler or grappler) to Smash Bros. that might make those who are not keen on his inclusion see worth in it.
It will be very interesting to see how Incineroar's inclusion is accepted by Smash Bros. fans. He is definitely no ROB (he definitely has fans), but he is definitely the odd one out of all the newcomers for Ultimate. He is the Jigglypuff for a new generation, and there is a definitely a charm to that seeing as how this game is a celebration for the entire Smash Bros. series as a whole.