Speed feats that involve dodging slow attacks that later become much faster

Minor Smash spoilers.

So, there are these feats where an explosion or waves are approaching to the protagonists, they are able to outrun it (even if briefly) or react to it, and after they get safe the explosion/waves are show to quickly go through or consume the world/galaxy/universe or whatever. Do the characters scale to the latter speed of the attack?

This happened on the ultimate Smash trailer, obviously, but there are more examples of it.

In The Fairly OddParents! Dictator Crocker uses some waves that Cosmo is able to outrun for a while, and when getting safe the waves quickly consume the world, would this feat count?

It's not that it got faster but that the first instant of its speed is it in comparison to the other characters speed.

Honestly, I just want a confirmation of the latter example being a legit speed feat. Is that an opinion or a fact?

For Cosmo? Yeah, unless it was stated to get faster over time then he should scale to the full speed of it.

Nice.