Samalet

Eh. I'll be honest, I'm not a fan of going over Lvl100. It breaks canon compliancy and immersion in a really bad way for me. I hope I'll grow to like it eventually though.

Just a Krabby as of yet, have to charge my phone first before going out there.

Unboosted Coba Berry Serperior doesn't actually OHKO Talonflame (80 - 99%) and Charizard Y (70 - 82%) with HP Rock. Life Orb is better IMO, especially since Talonflame beats you if the opponent uses Flare Blitz instead of Gale Wings.

Hyper Beam does 32 -38% to Exeggutor and Rest can work just fine in Gen 1, if you don't let your Mewtwo in on a Pokemon that can threaten it. What are Alakazam or Chansey gonna do to a sleeping Mewtwo? They can maybe 4HKO it at best. Edit: Scrap that, their standard sets 6HKO it. Also, add in Starmie, it's attacks do nothing to Mewtwo too. At +2 Psychic does as much damage as Hyper Beam to Starmie, Blizzard does more damage than Hyper Beam to Alakazam and it OHKOs Exeggutor. Hyper Beam just takes a valuable move slot away and gives you nothing in return, you can barely beat Chansey with it anyways, play Submission for that or just spam Psychic for the special drop.

It literally fails at 2HKOing Chansey 80% of the time. Possibly the worst move ever. http://imgur.com/4Fj1bXC Just use Amnesia Mewtwo with Psychic/Blizzard. You're better of Amnesia'ing to +6 and then spam Psychic against Chansey, but even then you still have a high chance of losing to it. Mewtwo can beat Chansey with Submission, otherwise no bueno.

I'm saying it again. Hyper Beam is not good on special Mewtwo and physical Mewtwo is inferior. Mew does that role better. Hyper Beam doesn't net KOs against the important Pokemon if they haven't lost >40% of their HP already. Then you lose a turn, which could cost you the best Pokemon in the game. It's absolutely not worth it.

Corrosive Acid Type: Poison Special BP: 80 PP: 20 Accuracy: 100% Hits Steel-type Pokemon for super effective damage, has 10% chance to badly poison the enemy. Freeze-Dry clone (to level the playing field, Freeze-Dry would be buffed from 70 to 80 BP too and be available to all Ice-type Pokemon). Learnable by every Poison type Pokemon and most Grass types (Move Tutor).

Running Rest over Recover solves that problem. Hyper Beam is problematic because it will only do a bit over 50% to Chansey and Starmie, plus you sacrifice a turn. If you really want to nail Chansey you can run Submission, which is much better for that purpose. Blizzard is normally the better coverage move, it packs enough power to 2HKO Alakazam at +2, OHKOs Exeggutor and gives you a shot at freezing your opponent.

Uhm, don't use Hyper Beam on special Mewtwo guys. Honestly, just go with the standard smogon sets, Amnesia Mewtwo w/ Psychic/Blizzard/Recover and Sword Dance Mew w/Hyper Beam/Earthquake/Soft-Boiled.