The Flash, the series, is not the one to shy away from showing characters who might be at par with Barry himself. Now, the question that keeps arising is as to why the creators would want to incorporate speedsters against Flash himself? Here are the answers.
In 'The Flash: Season 3, Flash is seen defeating Savitar and snatching the Philosopher's Stone which gave him immense powers. Now he has to dispose it so that it doesn't lands in evil hands. Henry Allen helps Barry to throw the Philosopher's stone above where Barry sees his girlfriend getting killed by Savitar