Pikachu @Light Ball
Timid, Static
Dunno about the exact values, but most of it's EVAs are placed in speed.
-Grass Knot
-Thunderbolt
-Signal Beam
-Magnet Rise
The Light Ball is the only reason to ever use Pikachu; even Red uses it. Pikachu is just way too weak without it, although getting one can be a little annoying. Unless it's in a double battle, Thunderbolt is generally superior to Discharge for more power. Grass Knot will let you hit the Ground types who otherwise wall you. Signal Beam hits grass types, and although it's not that great in and of itself, Pikachu doesn't have many options for attacks, its movepool sucks. Magnet Rise may seem unusual, but given the AI likely won't give you a chance to use set up moves or substitute (since they rarely set up or switch), it can allow you to catch slow ground types off guard, as the AI is terribly predictable with its Earthquakes.
You may be noticing I dropped pretty much all of the original moves, but it's mostly because of how Pikachu plays. Pikachu wants to hit hard and fast, since it cannot take a hit, period (most Subway/PWT standards can 1HKO it if it doesn't do so first), so trying to set up with Charge Beam, Charm, or Light Screen is generally a bad idea. Pikachu makes things like Azelf and Infernape seem like tanks; its defenses are downright horrid. Gotta go for Offense on this little rodent, or else he'll be dead weight in no time.
Venusaur @Big Root/Focus Sash
Modest, Overgrow
Again, not sure, but mostly placed in SP.ATK/DEF.
-Giga Drain
-Sludge Bomb
-Leech Seed/Growth
-Frenzy Plant/Sleep Powder
I know you say you want Frenzy Plant, but I really have to advise against the Elemental Hyper Beams if you're intending to do the Subway/PWT. You'll deal the same damage with Giga Drain across two turns, but without turning your self into dead weight (since the option to switch after KO'ing doesn't apply to Subway/PWT). Unless you're using it as the final attack to end the match, or if you'll be KO'ed that same turn regardless, it's almost never worth it, and is too unreliable. But, I kept it as a potential option rather than replacing it since you seem intent on it.
Sleep Powder can allow you to incapacitate a Pokemon completely, meaning it's a fantastic move to use if something that resists both of Venusaur's STABs shows up (Aka, steel types). Growth can be an option if you intend to use Sunny Day on Charizard, as Growth's effect is doubled in the sun.
As for Focus Sash... Big Root is kind of a waste for just Giga Drain. Never been too fond of it. Even though Venusaur does have a bit of bulk (making the Sash seem a little silly), Focus Sash guarantees that you will survive at least one attack, which, when combined with Sleep Powder, can guarantee you incapacitate your foe.
Charizard @Life Orb
Timid, Blaze
-Sunny Day/Focus Blast
-Flamethrower
-Solarbeam/Air Slash
-Blast Burn/Roost
While Sunny Day/Solarbeam on Charizard can be viable, I don't see it having much synergy with the rest of your team, as both Lapras and Blastoise hate it, and it can situationally screw up Venusaur. I listed both as viable options though, but if you do decide to go for Sunny Day, I'd put Growth on Venusaur, since Growth has its effect doubled under Sunlight.
Anyway... For the non-Sunny Day set, Air Slash is a solid STAB that works great on things that resist fire (Dragons, other Fire Types, Water types), and shreds fighting types. Focus Blast lets you nail the Rock Types that otherwise wall you. The shaky accuracy may be a deterrent, and the lack of Solar Beam makes water types more of a threat, but no setup is involved this way. And again, I have to recommend against Elemental Hyper Beams, as their cons outweigh their pros. Roost instead can allow you to shrug off Life Orb damage.
Blastoise @Leftovers
Bold, Torrent
-Scald
-Toxic
-Ice Beam
-Hydro Cannon/Protect
Dragon Tail doesn't do much for you, as the AI doesn't set up that often, nor are you using entry hazards, which are the factors that make Dragon Tail worthwhile. Switch it with Ice Beam to allow you to hit things that otherwise resist your STAB (Dragons and Grass types, notably). Same deal as before with the Elemental Hyper Beam, you know what I'm thinking by now. Protect, instead, can allow you to rack up Toxic Damage while giving yourself an extra turn to recover HP with leftovers.
Snorlax @Leftovers/Chesto Berry
Adamant, Thick Fat
-Body Slam
-Earthquake
-Sleep Talk/Crunch
-Rest/Fire Punch
Rest isn't really worth using unless you're planning on using Sleep Talk with it; otherwise, you're just going to get KO'ed while you sleep. I replaced it with Fire Punch, as it gives you a bit more coverage, letting you nail the steel types who're neutral/immune to Earthquake for more damage, as well as screwing over Ice Types and Bug types. Admittedly, it's also possible to replace Earthquake with Fire Punch, depending on your preferences. If you want to keep Rest though, replace Crunch with Sleep Talk. You may have a problem with Ghosts that way, but you'll have a problem with Steel types without Earthquake, so it's a matter of preference. Keeping Fire Punch is also an option for Rest Talk. Also, PWT and Battle Subway have the "Same item" clause, so if you're going to use Leftovers on Blastoise, you can't use them for Snorlax too. Alternatively, you can use a Chesto Berry, and keep Rest without Sleep Talk.
Lapras @Sitrus Berry
Modest, Water Absorb
-Psychic/Perish Song
-Surf
-Ice Beam
-Thunderbolt
Throwing Psychic on Lapras turns it into a pseudo-Starmie, but with STAB on ice and not Psychic (in addition to obvious stat differences). It rounds off the coverage by letting you hit Poison and Fighting types just a little bit harder. With its high HP, Lapras can sometimes survive a hit from a fighting type and bite back despite the weakness. Perish Song can take advantage of the fact that the AI doesn't really switch. Synergizes well with Blastoise's Protect to stall. It's sort of a last resort, though, on things you might have trouble with otherwise.
Shell Bell is rather... bad. You need to be doing A LOT of damage to make it even remotely worthwhile, and Lapras's offensive stats aren't enough to do that kind of damage. Sitrus Berry tends to be the better option, as Lapras's HP usually allows it to get into 50% range without being KO'd, and gives it a more reliable HP Boost than Shell Bell. It's not a perfect item for Lapras, but I'm avoiding Choice items since it's in game, and following item clause for the Subway/PWT.
Bonus points if you get what 0/1 refers to.
No bonus points for me :/
