Urgh ninjaed by 30 minutes
Just finished my playthrough of RBY.... again for 3 hours
Basically i expanded up Carl's post(and some copy paste sry)
-Availability: After Gym 3, once the player has made it to Celadon. Doduo can be found in RB at a rate of 25% between the levels of 18-22 on Route 16. In Yellow, it can be found at a rate of 35% between the levels of 22-26. Doduo can also be found on Route 17, 18 and in the Safari Zone. Wild Dodrio can also be found at level 29 at a rate of 1% on Route 17 in Yellow - that's probably not worth your time, though.
-Stats: Packing high 110 attack and 100 speed, Dodrio has insane offensive power. Its defense is nothing to write home about.
-Movepool: While extremely shallow, Doduo's move pool is tailor made towards its stats and typing. Through level up, it learns mostly normal and flying type attacks which are physical - notably Drill Peck at a mere level 30. It starts with Peck and Growl but can inexplicably be taught the Fly HM (conveniently located right on Route 16!) for a great, early attack. Doduo's move pool is so shallow that it actually wants the Fly HM; quite convenient.
While it learns Tri Attack naturally, TM49 can be obtained in the Celadon Department Store on the roof in exchange for a Lemonade. Not many pokemon can learn and effectively make use of the Tri AttackTM so it's a worthwhile investment on Doduo. It can also learn TM08 Body Slam(S.S. Anne) and TM10 Double-Edge(comes after Game Corner) for other normal STABs but Tri Attack will arguably suffice if those two TMs need to be saved.
Later, Dodrio can learn TM15 Hyper Beam which makes for a strong finishing move. Recommended move set for Doduo/Dodrio would be Drill Peck, Tri Attack, Fly, and one of Body Slam, Double-Edge or Hyper Beam.
Match Ups :
Blue(pokemon tower) : Gyarados gives some problem with Hydro Pump, Thrash, and Bulk. But if you defeat game corner + Erika first, Dodrio can sweep Blue easilly.
Erika : Assuming you caught level 22 Doduo, or even less, you can Spam Fly against the Gym, and do the same to Erika
Koga : You have tons of grinding chanced beetwen Erika and Koga, from the game corner, into the Pokemon Tower and the routes. The only problem with Koga, is poisons and misses. Sludge deals quite a damage to Dodrio, Double team and Poison can also slow down its sweep. In return, Dodrio 2Hko or 3HKO everything. With Hyper Beam, it owns the gym
Blue : Alakazam, provided it can survive Dodrio's assault(which wont happen with Hyper Beam) 2HKO's Dodrio at optimum level on this point. Charizard cant survive much of Dodrio's assault, but Slash deals plenty of damage. Basically its a winning match up in Dodrio's favor.
Sabrina : Surprisingly, Dodrio has quite the enough speed to outspeed her team. Therefore you can Drill pecks them. Its almost the same as Koga, It might struggles a bit in a 2HKO cases, but Dodrio can more or less sweeps when given the right movepool at sufficient levels(40+)
Blaine : Growlithe and Ponyta cant do much to Dodrio, since its pretty likely they get OHKO'ED. Rapidash and Arcanine can be handled by Hyper Beam
Giovanni : Rhyhorn cant do much against Dodrio. Nidoqueen and Nidoking lost to Drill Peck spam. Dont bother with Rhydon
Last Non Champ Blue : Gyarados and Blastoise is a hard match up since they usually can tank Dodrio's assault and counter with Hydro Pump. Rhyhorn can be attacked until its dead(did not worth the time). Alakazam is a matter of outsped or not. Otherwise, Hyper Beam can do the job to OHKO it
Lorelei : Most of them can survive and deliver an Ice Attack in return. Jynx can be Hyper Beamed to death. However, since its a five way battle, you night want to reserve the PP.
Bruone : Other than Onix, sweeps
Agatha : Some annoyment, but Dodrio can defeat everyone of her pokemon one on one. Its like Koga, in which most of the problem comes from status, but shes significantly easier tanks to the ease of which you can sweep with Drill Peck against her fragile team
Lance : Gyarados is always a problem albeit its pretty do-able, and Dodrio didnt like Aerodactyl's hyper beam. STABS alone allows you to handle the Dragonairs. Dragonite is a huge problem.
Champ Blue : Gyarados and Blastoise beats Dodrio, but it can defeat anything that can show up in his team.
Additional comments: A smart Doduo trainer will beeline west from Rock Tunnel to Route 16 immediately and make capture a priority. This allows for maximum opportunities to get Doduo up to par level and moveset wise. Probably one of the few notable downsides to Doduo is that it's slightly behind when you catch it. That said, Doduo's placement just outside of Celadon couldn't be more perfect. There are plenty of useful, new TMs that Doduo learns that become available in Celadon and many fodder trainers to use for experience growth, especially everyone in the 4th Gym. It also evolves at level 31 into Dodrio which is a huge power boost. No TMs are a must but it is recommended that the Tri AttackTM be used instead of waiting until level 45 for Dodrio to learn it. Fly is also recommended as there's space in the move set for it without sacrificing another attack. It's very handy when a roster mon can also assist with HM duties without any drawbacks. Doduo/Dodrio is a quick, straight forward attacker which has the ability to quickly one shot many trainer opponents with its high attack and speed and for that it deserves a spot among the better Pokemon in the game.
HUGE CREDITS to Carl because this is just an extended(yet unimportant) Copy Paste