Our kid wore the super-duper cute Pikachu costume (post coming soon) two years ago, and now that she has outgrown it, she wants her baby brother to be Pikachu while she could be Eevee. We only saw one really great one on Amazon so we decided to take a chance. Being authentic, it surely didn’t disappoint but it was definitely too big for her lol…
SAZAC Kigurumi – Pokémon – Eevee – Onesie Jumpsuit Halloween Costume – Kids Size (5-9 Year Old)

Review: This is an awesome piece of Eevee costume for kids! It’s authentic and it’s fluffy as it should be. We knew it was for kids 5-9 years old but we got it anyway since we love it so much! Will definitely use it when she grows into it!
Look how cute this look!
However, since she’s still too young / short for this…
In the meantime, we bought this:
GZHOK Unisex Kids Cartoon Pajamas Christmas Cosplay Costume Animal Polar Fleece
Review: It’s not as thick / fluffy but it fits and looks good enough for Eevee! We will stick with this one this year…