Snorlax
-Double Edge
-Curse
-Sleep Talk
-Rest
Charizard
-Fire Blast
-Earthquake
-Rock Slide
-Belly Drum
Venusaur
-Razor Leaf
-Sleep Powder
-Light Screen
-Synthesis
Forretress
-Toxic
-Spikes
-Rapid Spin
-Explosion
Raikou
-Thunder
-Reflect
-Roar
-Rest
Tyranitar
-Rock Slide
-Crunch
-Pursuit
-Roar
The role of Snorlax on this team is to take a sleep inducing move, and then dish out whatever damage it can. Snorlax is the best Pokemon overall at taking sleep inducing moves because there are no Pokemon who use sleep moves that threaten it with a super effective move, with the exception of Poliwrath, but you won't be seeing that in OU often. Sleep talking Snorlax is a good pivot to most Pokemon in the game and it supports its teammates here nicely. It's the main counter to Nidoking which threatens most of the other Pokemon on this team, depending on its move set. It likes to stay near full health in the event of getting p-hazed out a lot and accumulating spikes damage.
The role of Tyranitar here is to trap the ghost types for Snorlax, Charizard, Forretress, and Venusaur, as well as getting psychic types out of the way for Venusaur and Charizard. These three moves plus roar are perfect for what the rest of the team has trouble dealing with overall. Ideally you don't want any status besides paralysis on Ttar or else it's longevity decreases quickly. The normal resistance is appreciated as opposed to using Umbreon; having a second p-hazer is also useful to help with racking up spikes damage, or neutering baton pass threats.
Raikou's role is to add some extra defense to the others while spreading paralysis, p-hazing baton pass threats, and accumulating spikes damage. Reflect is useful especially in the case of Marowak, because the only two Pokemon you will normally be switching into Marowak are Forretress and Venusaur, and both take a decent chunk without reflect up. The reflect also helps Charizard set up belly drum in the face of certain physical attackers, as well it helps switching any Pokemon into a physical attacker much easier.
Venusaur has an important role on this team and helps Charizard out greatly. Light Screen is arguably the better screen of the two that Charizard can set up under without worrying about being taken out by a surf or thunder, with the exception of a critical hit. Venusaur also covers Charizard's weakness to water, and the immunity to poison is nice for switching into Suicune or Cloyster with toxic. Not only that, but it threatens to put a Pokemon to sleep, so you can usually guarantee a switch if you bring Venusaur in at a good time. Venusaur is also the main counter to Machamp on this team, so if they have it, ideally you want to put Machamp to sleep, for it it gets too many curses under its belt it can become quite a problem.
Forretress has the goal we all know that is setting up spikes and removing them. Toxic is the Best choice for this team simply due to the fact it can make Starmie, Cloyster, Snorlax, Rock and ground types, and many other Pokemon easier to handle over time. Toxic and Spikes on this team is crucial and it gives Charizard an easier time to take out its targets. Explosion needs no explanation, but on this team that power is too good to give up for another move, it threatens many switches which can also be used to an advantage.
Charizard is who should be dealing out the most damage, that is the goal of this team. Get it out on the field carefully and try to wreak as much havoc as you can. The standard belly drum set is preferred here over something like hyper beam, due to the team being rather slow overall, not hyper offensive. With the screens up Charizard is hard to deal with, because the typical counters no longer are able to counter it. Charizard doesn't want to lose its leftovers to thief, because if it is forced to switch out, the goal is to get it back up near full health where it can make another run. Charizard obviously doesn't want to take status in most scenarios unless you can see the trade off being worth it.
This is a solid team and a lot of fun to use, it has some obvious weaknesses, but that is the price when using two BL Pokemon in OU. Forretress or Raikou are usually my starters.