The default rarity is the minimum when a pet is learned. For wild pets this is usually "poor". Pets from other sources can be common, uncommon or rare by default.
Source:
Pet Battle
Expansion:
Legion
Owned by:
50.71%
Based on this many collections: 35892
Players who own this pet have it:
Once: 93.88%
Twice: 4.9%
Thrice: 1.23%
Strategies:
9
Popularity:
Low
Pageviews:
6512
Breeds:
BB, SS, HH, HP, PS PB, SB
Magic
Magic pets cannot be dealt more than 35% of their maximum health in one attack.
50% vs.
33% vs.
33% vs.
50% vs.
You have the odd feeling that it wants to kill you.
Source 
PvE 
PvP 
Other Info 
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