can you tell me what yoyo this is?

I think it’s a yomega brain but i’m not sure…

Looks to be a Yomega Brain.

but were any made without the atom picture?

I think it only is on one cap per yoyo so my guess is that the one in your picture is one that someone traded halves so the have no “Atoms”. That or they might have sanded it off. Maybe a misprint even can’t really know for sure.

and the different colored weights?

Yes it seems that some of the yoyos come with diffrent “Clutch” colours. Not sure if it’s rare or anything I never owned one myself.

Looks like a Franken-Brain, for lack of a better term.

Looks like there was a Yomega Brain fight and after it was done, someone assembled a winner from the set of surviving parts.

Hey, as long as it works, what difference does it make, right?