I think the battle of the Avatar and Infinite has some symbolism. Think about it, Shadow wipes out Zero's (Infinite's original name before it got scrapped or by the games logic rename himself that) Jackal Squadron but was then spared by him, and then Zero Wiped out the Resistance squadron that the Avatar was in and the thing they are common in is that they started off, as Zero/Infinite puts it; Feeble, Afraid and weak. Its only after the 2nd and 3rd fight where both The Avatar and Infinite gets even. Infinite relied on his own strength with the power of the phantom ruby and the Avatar got his strength by the cheers and encouragement of Sonic and his friends.
Kinda sums it all up nicely don'tcha think?
I think the battle of the Avatar and Infinite has some symbolism. Think about it, Shadow wipes out Z