Sundipped Superman vs Flash ( Wally ) with IMP.

Supes from JL#25 same sundip vs Wally who have built up his ultimate infinite mass punch, they collide, what happens?

This guy won’t even feel an imp.

If the imp is based off actual relativity then it all depends on how close wally can get to the speed of light precisely.
The mass of the punch is asymptotic.
That means the closer wally gets to the speed of light the more his mass grows indefinitely.
With enough precision, wally can gain the mass of the universe itself.

It takes precision, not being overly fast. For example, Going 2x faster than the speed of light will produce a weaker punch than going
1-1/(1e100) x the speed of light.

The flash would disintegrate upon impact.

Originally posted by Booya_69
The flash would disintegrate upon impact.

The speed force protects him from those type of effects.

Originally posted by h1a8
The speed force protects him from those type of effects.

As ridiculous as it is, yes.

And even regular speedsters have some degrees of protection against their own speed doing harm to them - even when it's not really consistent with their other showings (i.e. getting punked by street level attacks) and doesn't make a tiny bit of sense.

Originally posted by h1a8
The speed force protects him from those type of effects.

Well then wally gets punched across the galaxy.

In theory, Flash should be able overpower Supes if he builds up enough momentum & mass.

Hulk's Thunderclaps of course.

The Superman's punch trascended dimensions, isn't? He would wins.

Flash would annihilate Superman with that punch before Superman even knew what happened.