Ludicodaniel
<-If only it was red
Personally, I feel Shinji would be indifferent at first, until he actually flights them. Especially if he finds out they held their own against Legendary pokemon, such as Charizard fighting Articuno. He'd end up being impressed, and confused, about why Ash chose to start over, and see power isn't everything eventually.
I'd like to see Ash show Shinji that power alone isn't enough, by fighting with his most powerful pokemon, while using his own caring and somewhat unpredictable stratagies. (Eg: Classic Bayleef, Jump with Vine Whip to dodge and counter)
Finally, I think Charizard showing up to show Shinji a thing or two would be nice. That way we get to see it use some of it's newer moves, such as Air Slash, and Shadow Claw.
I'd like to see Ash show Shinji that power alone isn't enough, by fighting with his most powerful pokemon, while using his own caring and somewhat unpredictable stratagies. (Eg: Classic Bayleef, Jump with Vine Whip to dodge and counter)
Finally, I think Charizard showing up to show Shinji a thing or two would be nice. That way we get to see it use some of it's newer moves, such as Air Slash, and Shadow Claw.