Quoted By:
Immediately banned and would be the best Pokemon in the game hands down. Most of RBY is 2HKO'd by Slash, so it only needs coverage for resists. Earthquake smacks Gengar for 85%, and Blizzard brings Golem and Rhydon down into EQ range. It doesn't even need Thunderbolt since its normal STABs do way more damage to every Water type in the tier anyway, with only Cloyster having favorable odds of taking two Slashes back-to-back. Slap on Rest and you have a nearly unkillable wall-breaker with 150/100/95 bulk. NOTHING in the game comes remotely close to OHKOing Slaking. Snorlax's Self-Destruct peaks out just short of 70%, and +2 Surf from Slowbro doesn't even 2HKO. Not even Mewtwo can safely switch into it.
>Slash vs. Mewtwo on a critical hit: 222-262 (53.4 - 63.1%) -- guaranteed 2HKO
Slaking in RBY would make GSC Snorlax look like a fucking joke.