SellerChamp fully supports creating variations on:
eBay
Shopify
WooCommerce
For Amazon and Walmart, each item (including variation(s)) is required to have it's own ASIN (in case of Amazon item / variation) or UPC (in case of Walmart item / variation).
NOTE: It is recommended to create and manage variations for Walmart items directly on Walmart.
Click here to know more about how to create and manage variations through SellerChamp.