Board Thread:General Discussion/@comment-28303987-20160409204142/@comment-26242189-20160419035802

"Watch out for that Smiley Trash Bag. Let's just say, he gave me my fair share of resets."

Oh, so not even FLOWEY could beat Sans. In fact, it even says Flowey couldn't even defeat ASGORE! He "tried to get that stupid king to show me the souls, but he wouldn't"

Also, these are not EXACT quotes, but they're similar enough.

So Flowey isn't as powerful as you think. The only reason he can reset was because Alphys gave him that power.