For all his talk, Shadow genuinely believes Sonic is the true Ultimate Lifeform - not just physically, but in a moral sense.
While Shadow knew about Chaos Control and using the Chaos Emeralds to
power weapons like the Eclipse Cannon, he never knew it was possible to
achieve a super transformation until he did so with Sonic to stop the
Finalhazard. Between Sonic transforming, using Chaos Control with a fake
Emerald and fighting Shadow to a standstill without any boosts in power
a Chaos Emerald could give, Shadow is convinced Sonic is more than an
Shadow is also deeply ashamed of some of the actions he committed
during the Black Arms invasion and after Eggman awakened him, even more
so after the future Mephiles showed him. Shadow was astounded by how
quick Sonic was to forgive him.