Considering the timelines of both game development and movie development, I do think that it's feasible that what became Latias/Latios & Elhawk (which further became Blaziken) was something being designed so that the movie had some legends to show off from the upcoming game, followed by then spinning those pokemon out.
Like it seems like development really kicked off in earnest in 2001 and then oh hey by October they've already trademarked Latias & Latios, November 2001 minimum we already have near finalized sprites of them, and then they tease them with the 5th movie teaser that december. They were in the game before they finalized Kyogre & Groudon even, and it'd be a while before the regi even had something beyond their typings planned. It just kinda points that even if they weren't designed by the movie, they were probably designed with it in mind if that tracks
Like it seems like development really kicked off in earnest in 2001 and then oh hey by October they've already trademarked Latias & Latios, November 2001 minimum we already have near finalized sprites of them, and then they tease them with the 5th movie teaser that december. They were in the game before they finalized Kyogre & Groudon even, and it'd be a while before the regi even had something beyond their typings planned. It just kinda points that even if they weren't designed by the movie, they were probably designed with it in mind if that tracks
