Persona 5 Royal will feature special DLC that will see Persona 5’s Phantom Thieves facing off against the protagonists from Persona 3 and Persona 4.
As reported by Polygon, the news was revealed during a Japanese Morgana’s Report stream and will see these battles taking place in the Velvet Room as Challenge Battles, which are extra tough.
The trailer shows the Persona 4 (Yu!) protagonist with Izanagi and images from the Japanese Persona 5 Royal website show Persona 3’s protagonist (Makoto!) using Thanatos.
Source: IGN.com Persona 3 and 4 Protagonists are Boss Fights in Persona 5 Royal