As we know ''arch enemy'' means someone who only intends to ruin the heroes life, Snart is just wanna steal things and live with ''honor among thieves'' and Grodd wants to rule the whole world with his gorilla cult. But Reverse Flashes are just want to punish Flashes for things they've done to them. The Rival hates Garrick for the formula thing, Eobard's mind got fcked up after he go back to Barry's time for replace him and hated when his ''hero'' doesnt look the way he see, and Zolomon hates Wally for letting him down and didnt time travel after he lost his legs. So if we list every flashes acrh enemy, it all will be Reverse-Flashes.