What an intriguing question! Let's analyze the characteristics and abilities of each contender:

1. African Lion:
- Strengths: Powerful jaws, sharp claws, social hunting experience
- Weaknesses: Relies on coordination with pride members, vulnerable to attacks from multiple opponents
2. Silverback Gorilla:
- Strengths: Immense physical strength, robust build, intelligent
- Weaknesses: Limited combat experience, vulnerable to attacks targeting face and neck
3. Grizzly Bear:
- Strengths: Powerful claws, robust build, omnivorous adaptability
- Weaknesses: Solo hunter, vulnerable to attacks targeting face and neck
4. Anaconda:
- Strengths: Crushing constriction ability, stealthy ambush predator
- Weaknesses: Limited mobility, vulnerable to attacks targeting eyes and mouth

Considering these factors, here's a hypothetical scenario:

Initial Chaos:
The four animals are released into the cage, and initial skirmishes ensue. The lion and grizzly bear engage in a fierce battle, while the gorilla observes from a distance. The anaconda slithers away, seeking an advantageous position.

Mid-Battle:
The lion's social hunting instincts falter in this solo environment, and the grizzly bear gains the upper hand. The gorilla, seeing an opportunity, charges at the bear but is swatted away. The anaconda seizes the moment, wrapping its body around the distracted bear.

Endgame:
The anaconda's constriction proves too much for the bear, and it succumbs to suffocation. The lion, weakened from its initial battle, becomes the anaconda's next target. The gorilla, having recovered, attempts to rescue the lion but is too late. The anaconda then focuses on the gorilla, using its constriction to immobilize it.

Victor:
The anaconda emerges victorious, its adaptability, stealth, and crushing constriction ability proving too much for the other three contenders.

Please note that this is a hypothetical scenario, and in reality, such animal fights are inhumane and should never occur.