Their is no evidence of a encounter with Dasharatha
The claim of Dasharatha defeating Ravana comes from this fictional book: History of the Earth
This is what Dasharatha tells people about Ravana in the actual ramayana :
Thus when he is said so by that sage Vishvamitra, then the king Dasharatha spoke to the sage, "I myself am not capable of standing ...
After Sudama(Kuchela) was blessed with richness by Krishna, Sudama performed charity to brahmanas and meditated on Krishna. Sudama, along with his wife, reached Lord Krishna's supreme abode after his human life.
Engaged in meditating on Lord Krishna's lotus feet and giving charity
to the brahmanas, Sudama and his wife finally returned to Lord
In Rig Veda elimination of Vritra by Indra was mentioned .
According to the Rig Veda, Vritra kept the waters of the world captive until he was killed by Indra. Tvashtra fashioned the thunderbolt (Vajrayudha) for Indra. Thereafter, he defeated Danu, the mother of Vritra.
Indra killing Viśvarūpa or Triśiras - created by Tvaṣṭā to dethrone Indra, a part ...