I don't really understand the 2 Kid Flashes, but I can work some stuff out
Red-Head Wally was there before, but during the events of Flashpoint he got stuck in the SpeedForce, being wiped out from the Timeline
Thus, he was replaced by his cousin, who concidentally has the same name, Wally West (Black dude, best Kid Flash imo)
Then all of that stuff that we know, Red-Head remembers his past life and searches for his family and gets Dr. Manhattan Powers while Black Kid Flash gets to stay in that timeline.
But what are differences between them?
Who is the smartest? Strongest? Fastest?
What are their full names??
.Help me out bros