I'd suggest you go with RP over Substitute. One of the main advantages of Latios and Lando, along with their massive power, is the fact that ScarfKeldeo can't revenge kill them. That means that they only have to worry about that one counter Team 2 chooses before it can sweep. With Cube shuffling around damage, Lando has a much easier time pulling off a sweep with Rock Polish (which it can't do with Sub). The tricky part, though, is dealing with Heracross or offensive Latias which counters Lando (the former profits from the switch-in to fire off its powerful attacks while the latter has Roost to keep it going) as well as finding the opportunity to switch-in and set up. (these reasons are why I opted for LO Latios instead)