London: Uncapped Yorkshire leg-spinner Adil Rashid, 27, has been selected despite not being part of England's team-bonding trip to Spain.
Mark Footitt and Liam Plunkett, who is not fit, are not picked after going on that trip, but Steven Finn is recalled.
The first Test of the five-match series starts in Cardiff on Wednesday, 8 July.
Bayliss said Rashid is "in good form" and that he "spins the ball both ways and sometimes those guys are difficult to play".
The Australian told BBC Sport he wanted to "create a good environment that lacks pressure" in the England camp and that he would be "just as competitive as anyone else" when facing his native country.
Rashid is one of five players in captain Alastair Cook's squad - along with Moeen Ali, Jos Buttler, Adam Lyth and Mark Wood - who have not played in an Ashes series.
Finn is chosen ahead of fellow pace bowlers Plunkett and Footitt despite not playing a Test since he was dropped following the first Ashes Test in July 2013.
England squad for first Test: