WMG / Rudolph the Red-Nosed Reindeer (1998)

Ridley emigrated from Antarctica.

This would explain why he's penguin living in the North Pole.

Going by above mentioned theory, Ridley recruited his relatives from Antarctica to help Santa in his toy factory after the events of the movie.

Giving that Stormella is now living with Christmas Town residents peacefully, she decided to thank them somehow for the new ice sculpture. However, Ridley decided to do it for her. For this purpose, he told his family from Antarctica to come to the North Pole and help the elves make toys - especially since in the 21st century coming after 1999, children's requests for gifts to Santa Claus will be more difficult to fulfill than ordinary wooden toys or mascots (aka. video games, electronic toys etc.). This will also be rare justified example of Polar Bears and Penguins trope, with said penguins being immigrants from Antarctica.

Slyly family was killed by hunters.

There has to be some reason why Slyly at the beginning of the movie had this cynical mindset of his own, besides the whole "jerkish character tooks a level in kidness" cliche. Thus my theory of his family being killed by hunters. When he was a young pup/kit, human hunters hunting for arctic foxes had appeared in the area where Slyly and his family lived. Slyly, curious what these strange creatures could be, ventured into their camp ignoring his parents warnings. While exploring the camp (in the meantime taking a teddy bear belonging to the daughter of one of the hunters, who gave it to her dad to remember her), he accidentally woke up the hunting dogs who in turn woke up their owners. Scared, unaware Slyly led them to his family's burrow. Hearing the incoming hunters, his parents and older siblings sacrificed themselves to protect Slyly and his younger siblings while they were escaping. Not long after, the snow storm occured, resulting in Slyly and his siblings being separated from each other. This event resulted in Slyly blaming himself for the death of his family, and developing the mindset that you should cheat in order to survive, while the teddy bear he stoled from the camp being his de-stress item and the only object that reminded him of his family. The reason while he kept stealing Rudolph's stuffed toy is because the year before meeting Rudolph and Leonard he lost his own teddy bear while hunting for rodents in snow. This also explains his fear of Stormella's wolves - they remind him of the dogs that the hunters owned.

The Sprites blessed Rudolph with his red nose.

Given that at beginning of the movie they were singing his song that mentions his red nose and were later present at his house when his powers first manifested, I wouldn't call this a coincidence. They were also watching him through his entire life, which is suspicious, like how on Earth some fairies are watching over some random reindeer? Also, when they finally interacted with Rudolph they seemed too informed about how his nose works.

Reimaginings of characters from original Rankin/Bass specials, and how they will appear in 1998 movie continuity:

• Yukon Cornelius: A avid prospector and adventurer from small town in Alaska, who in his free time is a owner of animal shelter, as a reference to theory that his sled dogs were all strays before he adopted them. Slyly doesn't trusts him due to his family being killed by hunters, and thinking that Yukon will want to turn him into fur pelt too.
• Aeon the Terrible: For this reimagining of the character, Aeon isn't a giant millenium-old modern day vulture, but a Argentavis who got frozen in the Arctic during the Miocene period. After thawing out in 21st century due to global warming, Aeon goes to hunting spree and becomes a danger to residents of the North Pole. However, he still keeps his Woobie, Destroyer of Worlds aspect from his original appearance, due to being prehistoric animal who now lives in the modern world, which makes him unable to adapt to the new surroundings he found himself in.
• Big Ben: A humpback whale who occasionally visits the North Pole.
• Clarice: One of the Rudolph and Zoey classmates.
• Fireball: One of the Rudolph and Zoey classmates that maked fun of the latter red nose.
• Hermey the Elf: This version of Hermey isn't Rudolph's friend but a Christmas Town resident dentist. He's also adult by the time Rudolph gets born.

Reindeers with glowing noses are discriminated by other reindeers because they attract predators.

The glow attracts predators at night, thus putting all of the other reindeer in danger. But given that reindeer from Christmas Town don't have to worry about predators, this "excuse" doesn't justify the bulling Rudolph has gotten over the years.