He inherited the Sage's Yang Energy (Vitality), but needed hard-work and support from others to awaken its power at its fullest. Him not inheriting his father's powerful genes in context insinuated that Ashura wasn't naturally gifted and needed hard-work to be strong. This is explicitly why Ashura was compared to Naruto who needed hard-work to be strong in spite of his parents being prodigies.
As for the topic, I'm of the belief that Ashura inheriting the Sage's Yang Energy enables him to form his own Avatar with purely chakra alone in the same manner that Indra can. Ashura has the "Sage's Body" which gives him his own Avatar in the same way that Indra has the "Sage's Eyes" which enables him to manifest Susano'o.