The curious case of King Rishabhadeva
In the case of King Rishabhadeva, it is the exact opposite of Buddha- a legitimate avatar of Vishnu being pitchforked as the founder of Jainism. In fact King Rishabhadeva did not create any new religion. It was done so by his so -called 'disciple' Arhat
King Rishabhadeva's story appears in four adhayas of the fifth skanda of Srimad Bhagavtham.
King Rishabhadeva was a devout king, in fact the very embodiment of Vedic Knowledge. When his sons were grown up, he entrusted the kingdom to the eldest one, Bharata and after instructing them on the highest knowledge (this is described in the fourth adhyaya) he begins to practice what is known as Jada Yoga- which means a kind of yoga wherin a person totally neglects his body and tries to forget that he has a body. This kind of yoga is very difficult to perform, but Lord Vishnu took this avatar to show that it is possible.
Lord Rishabhadeva became an avadoota and wandered here and there, with no clothes on his body and the hair on his face and head, all long and unkempt. People - even his own subjects-began to think him as a madman. thus wandering Rishabhadeva reached the southern state of Karnataka (the region of Konkana, Gokarna and Venka) . By this time, long creepers had entwined his hands and legs but he did not care. He stayed for sometime in the forest near a place called Kutaka and later when a fire engulfed the forest, he gave up his life.
The news of a saint / madman living in the forests reached the ears of the local king called Arhant. He began to imitate Rishabhadeva's lifestyle and taking advantage of Rishabhadeva's name began to create a new religion which rejected the authority of Vedas and believed only in self mortification of the body. This was the beginning of the Jain religion.