Cartels, a form of collusive oligopoly, are often deemed illegal due to their anti-competitive practices. By joining forces and making collective decisions on price and output, cartel members effectively eliminate competition in the market. Such behaviour results in artificially high prices, reduced product quality, and limited choices for consumers. Moreover, cartels can stagnate innovation since member firms are not incentivised to improve or diversify their offerings, knowing that their position in the market is secured through the cartel. The net welfare loss to society, through reduced consumer surplus and potential deadweight losses, makes cartels undesirable from an economic perspective. As a result, many jurisdictions actively monitor and penalise cartels to maintain market competition.

Price leadership refers to a form of tacit collusion in oligopolistic markets where one dominant firm, often the industry leader or the largest player, sets the price, and other smaller firms in the market simply follow. The leading firm's price becomes the benchmark for others. This pattern might arise to avoid explicit collusion, which is illegal in many regions, while still achieving some degree of pricing stability in the market. Smaller firms find it beneficial to match the leader's price rather than engage in competitive pricing, which might ignite price wars. However, it's essential to understand that while price leadership resembles collusive behaviour, it doesn't involve formal agreements among firms.

Brand loyalty plays a pivotal role in shaping pricing strategies in oligopolistic markets. When consumers are loyal to a specific brand, it provides the firm with a degree of pricing power. Such firms can maintain or even raise prices without losing a significant portion of their customer base. This is particularly beneficial in an oligopolistic setting where price reactions of competitors can be unpredictable. A strong brand loyalty can act as a buffer against price-based competition, allowing firms to focus on other aspects like product quality, innovation, or service improvements. Moreover, brand loyalty can deter new entrants into the market, as they might find it challenging to sway loyal customers of established brands.

In a non-collusive oligopoly, firms actively compete against one another, rather than cooperate. This intense competition can lead to several benefits for consumers. Firstly, it can result in competitive pricing, ensuring that products or services are available at reasonable rates. Secondly, in an attempt to differentiate themselves, firms might innovate, leading to improved product quality, features, or newer product offerings. Additionally, non-collusive oligopolies might engage in non-price competitions, such as advertising, promotions, or improved customer service. Overall, the competition in non-collusive oligopolies can foster an environment where consumers enjoy better prices, quality, and choices.

Price wars in oligopolistic markets can be detrimental for all involved parties. When one firm aggressively reduces its prices to capture a larger market share, competitors, due to the interdependent nature of an oligopoly, are compelled to follow suit. While consumers might benefit from lower prices in the short run, the firms face shrinking profit margins. Over time, these reduced profits can inhibit reinvestment, research and development, and overall growth of the industry. Moreover, prolonged price wars might lead to financial distress for some firms, particularly those with lesser financial reserves. Therefore, to maintain sustainable profit levels, oligopolistic firms often avoid engaging in price wars.