The strumming pattern for “One Love” is a basic downstroke on the offbeat which is explained in detail in my video lesson “This song sounds great on acoustic guitar, and if your are using electric guitar then use a clean tone for your amp settings and make sure your right hand attack is short and crisp. The barre chord shapes I have suggested are all in one position for smoother voice leading and so you won’t have to go up and down the neck.