After a long journey full of ups and downs the player now stands face to face with the strongest Pokemon Trainer in the world: Red.
As the final boss of the game Red has the strongest team you would have seen up to this point by far: Pikachu, Moltres, Tyranitar, Snorlax, Suicune and Mewtwo. A Pseudo Legendary, Snorlax which is considered to be the one of the best Pokemon in GSC, as well as three legendaries means that your strategy and team building will need to be on point in order to secure the victory.
The iconic Pikachu is Red's lead as usual and this time its' Special Attack has been doubled with a held Light Ball, making STAB Thunderbolt pretty painful, it also has Surf to check Ground types, Thunder Wave to paralyze you, as well as Iron Tail for extra coverage. It's stronger than in the base game, but it's still easy to deal with as long as you can outspeed and use Earthquake, Pikachu will not withstand any strong attacks. But don't let Pikachu lull you into a false state of security, the real battle has just begun.
Moltres is next and it can do a lot of damage thanks to STAB Fire Blast which is boosted by a held Charcoal, STAB Sky Attack, as well as Solarbeam to counter any Ground, Rock or Water types. It also has a recovery move in the form of Morning Sun. Moltres is pretty likely to withstand at least one super effective attack and it can deal a lot of damage in return as it's very hard to resist all its' moves, a fast Rock type that can OHKO like Aerodactyl would be the perfect check for Moltres, but any strong attacker with Rock Slide will work as long as they can withstand an attack or outspeed.
Tyranitar it is a mixed sweeper with a held Quick Claw. It has STAB Rock Side and STAB Crunch, as well as Earthquake and Thunderbolt. Tyranitar has incredible Attack, good Special Attack and great bulk so it can be a big threat, especially if it gets lucky with Quick Claw. The best answer here is a Fighting type that can outspeed it, one thing to note here is that Typhlosion will not always be able to OHKO it and it's sure to get KO'd by Earthquake so you will need chip damage there or to put it to sleep in order to be safe.
Suicune is Red's next Pokemon and it can be a pain to take down thanks to a combination of great defenisve stats, solid defensive typing as well as a combination of Rest + Sleep Talk and a held Leftovers. It also has Surf and Ice Beam as attacks, Ice Beam means that Grass types aren't a safe counter. Still, it has no status moves or no super effective attacks against Electric types so that is the best choice here, especially Lanturn which can hit it with Thunderbolt and resist all of Suicune's attacks.
Snorlax is a very painful Pokemon to deal with for multiple reasons. It has incredible Special Bulk, very high HP, an excellent defensive typing, as well access to Curse that esenetially lets it boost Attack and Defense for free as it's unlikely to go first anyway, with one Curse up Snorlax will be very tanky physically and even Fighting types may struggle to 2HKO it. To make matters worse it has a held Miracleberry which lets it recover from any status for free and Red will attempt to exploit that with Snorlax having Rest, esentially giving it a free full HP recovery once. For offensive moves it has STAB Body Slam which can paralyze and Earthquake to deal with Rock, Ground and Ghost types which would otherwise be safe. The best way to deal with Snorlax is to 2HKO it with a Fighting type or try and infilcit status on it like sleep or Toxic. One thing to note here, despite having Earthquake there is one Pokemon that is completely safe here: Noctowl. Thanks to being a Ghost/Normal type Snorlax will not be able to inflict any damage and it can be defeated easily with a combination of Hypnosis and Nightmare, keep in mind however that the AI can switch.
Mewtwo is the strongest Pokemon in the game and is a worthy ace for the final boss of the hack. It has incredible stats all around with no weak spots, 130 Speed, 154 Special Attack, 110 Attack. Those are terryfing numbers and Mewtwo has the coverage to easily take advantage of it. It also has high HP and it isn't frail either, if you do not have a counter or a status spreader you will lose, as Mewtwo can singlehandedly demolish any team, tired or otherwise. STAB Psychic boosted by Twistedspoon, Flamethrower, Ice Beam and Submission gives it an incredibly diverse offensive arsenal, not even Dark types are a safe bet here, and a dedicated special wall like Blissey will get destroyed by Submission. Thankfully Mewtwo does not have a Miracleberry so it can be paralyzed, that will be the ticket to victory here. Slowking is by far the best option here with high special defense, Thunder Wave and most importantly resistances to all of Mewtwo's moves.