ATTN: Somewhat-Uber post INCOMING
About the ability: No Magic Guard, please. This gy will end up being a mixed sweeper pokémon, and you want to give him a 30% boost item, with no drawbacks? 4x weak to SR is bad, but we can cancel it somehow... Shiver looked like a good idea, but maybe Fresh Powder is a better name.
About the pokémon: WTF, MegaMewtwo. That fairy was WAY too close to my concept of Himath. The difference is, your sister's has a resemblance with Butterfree, while mine was like Venomoth... And the snowflake wings are obligatory.
About what in hell will the pokémon be: Either Mantice or the frozen Butterfree. But, as I'm a sucker for Himath, I like the fairy better. And she'd be just special-based, but with some move made to cripple Blissey, the top-class Special Wall. Like Garchomp and his Draco Meteor.
About the movepool and stats: Well, here we go.
Three-stages pokémon: Himarva, Himacoon, Himath (kill me for the names);
Evolution method: Himarva at level 30 OR Himarva at level 20-25 holding Protector ==> Himacoon at lv.55 OR Himacoon at lv.40-50 holding Beautiful Skin ==> Himath.
Trait: Frozen Skin, a Ice-Type Flash Fire, and Levitate. That was the original idea. Now, I'm thinking about a Ice-Type Water Absorb, as Ice Beams and Shards and Punches are pretty overused. This would somehow compensate for the glaring SR weakness, but only restoring 25% HP. However, this doesn't solve the Ember and Rock Throw weaknesses...
Base Stats: Remember kids, I created Himath during the Garchomp overhype, and she was planned to be a special version of him. So, the stats are HP: 100 / Attack: 80 / Defense: 88 / Sp. Attack: 135 / Sp. Defense: 95 / Speed: 102 / Total: 600.
Movepool:
Physical movepool:
Body Slam
Icicle Spear
Reversal
Beat Up
Ice Ball (huh, what)
Bug Devour (what is the US name again?)
Wing Attack
Ice Shard
Rock Slide
U-Turn
Earthquake
Brick Break
Aerial Ace
Fling
Avalanche
Special movepool:
Silver Wind
Ice Beam (duh)
Bug Buzz
Discharge
Thunderbolt
Thunder (there was a good reason I gave her these moves... I think that was because she lived on top of the mountains, near to the clouds, and had some lightning control... I think only Discharge would be good enough, though.)
Focus Blast
Brine
Charge Beam
Flash Cannon
Support movepool:
Embargo
Baton Pass
Camouflage
Spider Web (huh, what)
Barrier (the cocoon form; seriously, maybe I went too far...)
Mirror Coat
Rapid Spin (OH YEAH DELIBIRD POWER)
Sheer Cold
Hail
Haze
Roost
Whirlwind
Featherdance
Agility
Nasty Plot
Light Screen
Rain Dance
Safeguard
Snatch
Thunder Wave
Swords Dance
Stealth Rock (lol)
Trick Room
Signature move:
Frozen Wind - Ice-Type Overheat.
... Okay. Now that was truly huge and unnecessary. Obviously, a fuckload of moves can be removed, and I'll start now.
First, only Discharge. She doesn't need Boltbeam, neither Thunder Wave. Discharge has that 30% paralysis chance, anyway.
Why the fuck are Ice Ball and Brine there. Go away.
And then, the support options... I thought I created her for a special-based role ._.
But anyway, Roost, Hail and Sheer Cold will stay, duh.
I don't see why Featherdance, Camouflage and Whirlwind should be removed.
Who cares about Rain Dance, Safeguard and Snatch.
Instead of Barrier, Reflect would be better, I think, to go along with Light Screen.
Spider Web + Baton Pass is a nice combo, but she isn't a spider...
Everyone learns Stealth Rock, anyway.
And Haze? Almost no one learns it, let a mountain pokémon learn it, just for a change.
I think Mirror Coat should get along well with this pokémon if we decide to give her Magic Guard, but I wouldn't miss this move anyway.
Rapid Spin on a pokémon 4x weak to SR is laughable, but does anyone see a problem with it?
Trick Room should go away too. Why would a 102 Base Speed pokémon use it...
Now, Baton Pass, Nasty Plot, Swords Dance and Agility. The four would be way too broken together (hi Mew), so I think they can be ditched. I like the Baton Pass fairy idea (hi Ledian; okay, not a fairy), so I'd keep it. She's fast enough to not really need Agility; Nasty Plot is almost obligatory, as she is a special-basd pokémon; and Swords Dance would be great for a mixed sweeper, maybe even instead of Nasty Plot.
As I'm going for a special sweeper, I'd say Baton Pass and Nasty Plot are the moves to keep.
So be it. Removing the retarded moves, we end up with a nice special sweeper, with a interesting but not really useful physical movepool, with a incredible special movepool, having pseudo-Boltbeam, Bug Buzz for the Psychics and Dark-Types, and Focus Blast and an Ice-Type Overheat for even more destruction and specially for Blissey, along with Nasty Plot, to ensure the fat egg's doom (Nasty Plot once, use Focus Blast when Blissey switches in, finish her with Frozen Wind). Not only that, but she has a reliable recovery move, Plotpassing, the somewhat random Rapid Spin, and even pseudo-hazing.
Yeah, pretty OU, I know, but this one was meant to be OU. Remember, Garchomp's special-based sister...