Hedgehog
Hedgehogs demonstrate reasonable adaptability, having successfully colonised environments ranging from European woodlands to suburban gardens. They consume a varied diet of invertebrates, and some populations have learned to exploit human food sources, including the contents of cat bowls left outdoors by optimistic pet owners.
However, their response to motor vehicles suggests adaptability has limits. Curling into a ball, whilst effective against foxes, proves catastrophically ineffective against a Ford Transit.
Ninja
Historical ninjas demonstrated extraordinary adaptability, functioning as spies, assassins, saboteurs, and information gatherers depending on mission requirements. They infiltrated every level of society, from peasant villages to castle compounds, adjusting their methods to each unique scenario.
Modern cultural adaptability has proven equally impressive: ninjas now appear in films, video games, and children's birthday parties with equal credibility. The Teenage Mutant Ninja Turtles franchise alone has generated over $10 billion in revenue.
VERDICT
The ninja's ability to adapt methodology to circumstance, combined with remarkable cultural staying power, outperforms the hedgehog's more limited environmental plasticity. One imagines a hedgehog would struggle at a children's party.