If you thought that Toys "R" Us (NYSE:TOY) and Amazon (NASDAQ:AMZN) were mixing it up in the legal equivalent of Rockem Sockem Robots, it may very well become a battle royale now that GameStop (NYSE:GME) is entering the ring.

The popular video game retailer has teamed up with Amazon to roll out its new online storefront. The move is unusual in a couple of ways. First, it adds fuel to the fire of the Toys "R" Us claims that it is paying up for exclusivity, even though video games were never really the issue in the legal scuffle.

Yet the real fireworks lie not in the details but in the bloodline. Do you know which company spun off GameStop and still retains a meaty financial interest in the venture? Well, it's Barnes & Noble (NYSE:BKS). These are certainly odd bedmates given how Amazon and Barnes remain fierce competitors in their flagship bookselling ways.

With Borders (NYSE:BGP) already an Amazon partner when it failed at making its online bookstore profitable on its own, is it safe to say that the road to online enrichment runs through the Amazon? From Target (NYSE:TGT) to Office Depot (NYSE:ODP), the bricks-and-mortar titans have come knocking on Amazon's virtual door to gain entry into e-tailing haves after struggling as have-nots. Wasn't it really just a matter of time before Barnes and Amazon were tied to the financial success of a single venture?

Yet the real winner here -- beyond whoever collects on having to keep Amazon's deservedly elevated ego in check -- might actually be Electronic Arts (NASDAQ:ERTS). Yes, EA. All day today, folks making a purchase at the new GameStop store will receive a free copy of EA's Sims Online for the PC.

With EA's chances of growing the online base of Sims users -- and collecting $9.99 a month after the first trial month -- all but certain, it's not Rockem or Sockem that stands to ultimately land the knockout blow.

Both Amazon and Electronic Arts have been worthy Motley Fool Stock Advisor recommendations in the past.

Can a retailer succeed online without going through Amazon? Yes, there are quite a few out there, but is it a viable strategy or is it best to just embrace Amazon? All this and more -- in the Amazon discussion board. Only on Fool.com.

Longtime Fool contributor Rick Munarriz has been an Amazon customer since the 1990s -- but he does not own shares in any of the companies mentioned in this story.