Williams, 36, is about to release his first single, The Flood, with the band in over 15 years and he said he will do whatever it takes to get the band to number one.
He said to UK newspaper Daily Star: 'If all else fails, nakedness in Trafalgar Square. We might have to get our s out again. It's going to be an interesting week.
'JLS are great. When my last album came out and I was No 2 and they were No 1, I gave them a bell and congratulated them, so if the reverse happens, they have my number now.'
Take That's first ever single, Do What U Like, was released in 1991 and saw them strip off and flash their backsides that were covered in jelly.