I try to boycott Walmart too but they're hard to avoid with four large stores in St. John's. One of them is smaller and more centrally located in the West End, but the others are all enormous and on the edges of the urban area.
The only saving grace here is that St. John's is still a city where local rules. It's hard to even find chain restaurants in the Downtown, and there are lots of large, popular, local alternatives to chains in just about every retail category.
For the Walmart crowd, our local equivalent is Pipers. They have a smaller selection, and slightly higher prices, but it's a much more enjoyable shopping experience in much more central locations.
The only comparable competitors are Target (which is also out in the middle of nowhere) and Pipers (which has a smaller section, but has centrally-located stores peppered throughout St. John's).
Pipers is the one I choose if at all possible.