A reference to the Enron Corporation. Both are primary energy companies (Endron is an oil company, Enron was focused on electricity and natural gas) that have become conglomerates with diverse business interests. Enron also had a division called Enron International.
Similar to Avalon Hill, a publisher of wargames and strategy board games. Like Avalon Inc their games are focused on war and violence.
King Breweries and Distillers
A reference to Anheuser-Busch. They produce Budweiser which is marketed as the "king of beers". Like King Breweries, they have been accused of marketing their products to teenagers.
Herculean Firearms Inc.
Refers to Olympic Arms, who was party to a number of lawsuits regarding the constitutionality of firearms regulations. They are also the manufacturer of the AR-15 and M16, which matches the description of Herculean Firearms as a manufacturer of automatic and semi-automatic weapons.
An international fast-food franchise, O'Tolley’s is a pastiche of McDonald's. The Scottish "Mac" is replaced by the Irish "O'," the similarity between "Donald" and "Tolley" in sound, and the description of the chain as "the family place" matches McDonald's corporate branding in the late 80s-early 90s.
Sunburst Enterprises International
A reference to Sun Microsystems, a company that produced server hardware and technologies.
Young & Smith
This manufacturer of household pharmaceuticals is a parody of Procter & Gamble. It's also two prominent figures in Mormon history.
Black Dog Game Factory
A reference to White Wolf Publishing. Many of White Wolf's games are about supernatural creatures and their conflicts with each other and mortals. Black Dog's games are about "tragically hip antiheroes who kill and maim the uncool mortals in their paths, all the while moaning about their tortured souls." For more on BDGF, you can read this answer.
Black Dog also was White Wolf's imprint label for "supplements with mature and adult themes" (here).
... and several are pastiches
In addition to the companies that above that appear to be parody, there are several entries that seem to be pastiches of entire industries. Although the names may reference real companies, the details are drawn from different companies in the same industry.
- Hallahan Fishing Company is reminiscent of H&N Fishing Company, one of the largest seafood companies in north america. Hallahan is noted for illegal whaling and covert ops, but I could not find any mention online of real-life H&N engaging in these activities. There are allegations of various fishing companies being engaged in whaling (or harming endangered sealife). Some real-life company seems to have hired private security and investigation firms to dig in to environmental groups.