This is my Second list of Pokemon that I know are in this location and my rating on your chance on how likely you are to find them and maybe even some tips.
Unlikely / Rare 1 - 100 Good Chance / Not So Rare
Snowpoint Town:

Regice - 25/100 to 35/100 - Not So Rare But Not Too Easy To Find - No Side Notes.

Goldeen - 30/100 to 50/100 - Not So Rare But Some Times Easy To Find - No Side Notes.

Dewgong - 45/100 to 60/100 - Not So Rare But Some What Easy To Find - No Side Notes.

Smoochum - 35/100 to 55/100 - Not So Rare But Some Times Easy To Find - No Side Notes.

Jynx - 40/100 to 50/100 - Not So Rare But Some Times Easy To Find - No Side Notes.

Shellder - 30/100 to 45/100 - Not So Rare But Almost Some Times Easy To Find - No Side Notes.

Snover - 85/100 - Adverage Pokemon - Very Easy to find most of the time.

Spheal - 65/100 - Adverage Pokemon - Some What Easy to find.

Sneasel - 50/100 - Adverage Pokemon - Some Times Easy to find.

Swinub - 50/100 - Adverage Pokemon - Some Times Easy to find.

Delibird - 50/100 - Adverage Pokemon - Some Times Easy to find.

Psyduck - 40/100 - Adverage Pokemon - Some Times Easy to find.

UnownB - 5/100 to 15/100 - Rare And Not Too Easy To Find -
Shows Up At Random

UnownD - 5/100 to 15/100 - Rare And Not Too Easy To Find -
Shows Up At Random

UnownW - 5/100 to 15/100 - Rare And Not Too Easy To Find -
Shows Up At Random

That's very helpful! But how did you get ratios on their occurrence?

We do not need this, every poke has a equal chance of being found.