Ho-oh's appearance is nothing short of amazing. As Latios points out, Ho-oh rarely shows herself to humans. The fact that Ash already saw Ho-oh on his first day as trainer, let alone meeting her in person is a sure sign of Ash's skill and greatness.
Pidgeot return is awesome. Ash re encounters the Fearow that gave him trouble when his journey began, but unfortunately Latios and Latias are currently absent. Just as Fearow nearly kills him, Pidgeot decks him in one hit, sending him spiraling into a tree.
A New Chance for Adventure
An subtly awesome moment for Ash: when Tyson and and the Iron Masked Marauder are ordered by Giovanni to go after Ash, Giovanni tells them that unless it is 100% possible to go after Ash, they should steer clear of him. The fact that Giovanni, a powerful crime boss, who is currently sending these two to infiltrate Team Magma, is apprehensive about attacking a 12 year old boy says a lot about how far Ash's reputation has come.