Complex sentence: At Royal Rumble, Brock Lesnar successfully defended his WWE World Heavyweight Championship against John Cena and Seth Rollins in a triple threat match, while the 2015 Royal Rumble match was won by Roman Reigns, granting him a main event title match against Lesnar at WrestleMania.
Split into simpler sentences: At Royal Rumble, Brock Lesnar successfully defended his WWE World Heavyweight Championship against John Cena and Seth Rollins in a triple threat match. Meanwhile, the 2015 Royal Rumble match was won by Roman Reigns, granting him a main event title match against Lesnar at WrestleMania.