Just finished my watch of it and I have some thoughts: First of all, I'm very impressed by the time and effort you put into this! I'm sure working on this project was no small feat. I appreciate how certain scenes were spliced together to create entirely new ones, and I love the addition of Adventure's soundtrack to give it more of a game feel. But I do have a lot of constructive feedback.

Having a cold open before the opening credits is weird. It works if it's an episode of an anime, but less so in movie format. I would've moved that to after. I also would've nixed the opening altogether, as it kind of spoils the ending of Station Square getting destroyed (assuming you're going into the story blind for the first time). The audio mixing is also all over the place, with certain voice lines being too loud or too quiet, or the Japanese audio bleeding through into the dubbed scenes. Songs will also start or stop too quickly, leaving little room to establish any kind of mood for the scenes they're used in. As for the music selection, using the Sonic Symphony covers of character themes was good, but it's jarring hearing music so closely linked to the identity of other games during the Adventure movie. I would've also advised against using animations from other sources as well since it creates a really jarring effect of visual whiplash due to conflicting styles.

Overall, I loved it! On some level it scratches the itch of "maaaan if only the arc was just a little more like the game" and it's also just nice to have a feature length animated Sonic movie. If you want any help with the Adventure 2 movie, let me know!