Meditite has solid counters such as Slowpoke (and ghost pokemon with a little prediction) whereas Murkrow's counters aren't always reliable.
With Evolution Stone:
28 Atk vs 25 Def & 28 HP (75 Base Power): 12 - 16 (42.86% - 57.14%) - Average of 50.00%
Not exactly solid in my opinion, predict wrong, get a ThunderPunch to the face, and it isn't hard to predict a Slowpoke switch in at all. After that hit, the ball is in Meditite's court as to whether you switch to something else, predicting another ThunderPunch, or stay in to recover, expecting a Drain Punch or something. If Slowpoke does anything except Recover, it will be 2HKOd. Sure it has Regeneration, but your other Pokemon do not.
Meditite on the other hand really isn't that bad. He's slow and has to rely on wall-breaking to be useful in my opinion. He is revenge killed by anything faster than it and strong (flying and ghost moves aren't that hard to get people). In addition, stong pysically defensive pokemon that resist its STABs can do pretty well against it. Slowpoke can do well, and for those of you who like Thunderpunch, you can be walled by Riguree (believe it or not, Riguree is really good and is almost a perfect Meditite counter). Meditite is a good wall-breaker, but its too slow, too vulnerable, and isn't over-the-top great.
Meditite isn't as frail as you're making him out to be, it usually only is OHKOd by Murkrow and Misdreavus, one of whom a suspect themselves. For example, a Scarf Chinchou or Snover's Hydro Pump or Blizzard respectively, only does:
15 Atk vs 18 Def & 21 HP (120 Base Power): 12 - 15 (57.14% - 71.43%)
While Meditite will OHKO them both back with Drain Punch (or with Bullet Punch after that, if they're some odd super Bulky version), which puts Meditite's HP back slightly above 70% eager to destroy another Pokemon.
Things like Murkrow take this much from a Bullet Punch, assuming they have neutral nature Defense and 0 HP / 0 Def EVs and no Evolution Stone:
28 Atk vs 10 Def & 22 HP (40 Base Power): 8 - 10 (36.36% - 45.45%)
So basically after they Brave Bird something, they're dead. Misdreavus on the other hand, only has a chance being OHKOd with Zen Headbutt, when it doesn't have an Evolution Stone:
28 Atk vs 12 Def & 22 HP (80 Base Power): 19 - 24 (86.36% - 109.09%)
However, with an Evolution Stone (and sometimes Oran assuming it doesn't get High Damage Rolled) it nearly dodges the 2HKO from Zen Headbutt and Bullet Punch. Any prior damage will take it down though, and with Pokemon like Munchlax around and no recovery, Misdreavus would likely only be able to switch into Meditite once.
Elgym really is the only Hard Counter atm (or other obscure things such as Shelmet, which are hard to fit on a team), although it isn't exactly easily slipped into a team. In terms of walling, it is a far worse Slowpoke in just about every other situation, except for stopping Meditite. But even then, Meditite with a Life Orb and Return, although very rare, can always 2HKO it with Stealth Rock, even if it has a +Def Nature 252 HP / 252 Def EVs. So if Elgym ever does rise in popularity (I have only ever seen it once before in Gen 5 LC), Meditite can still take on its arguably best counter.
Here's some calcs:
Meditite (M) @ Evolution Stone / Life Orb
Trait: Pure Power
EVs: 116 HP / 196 Atk / 196 Spd
or 196 Atk / 76 Def / 196 Spd (with Life Orb)
Adamant Nature (+Atk, -SAtk)
- Drain Punch
- ThunderPunch
- Ice Punch / Zen Headbutt / Return
- Bullet Punch
Vs.
Elgym (Riguree) (M) @ Evolution Stone
Trait: Synchronize
EVs: 236 HP / 236 Def / 36 Spd
Bold Nature (+Def, -Atk)
- Calm Mind
- Psychic
- Thunderbolt
- Recover
(I don't know about the set, really only thing I could think of for an anti-Meditite set, but still being useful for other things.)
With Evolution Stone:
28 Atk vs 24 Def & 25 HP (75 Base Power): 7 - 9 (28.00% - 36.00%)
28 Atk vs 24 Def & 25 HP (102 Base Power): 9 - 11 (36.00% - 44.00%)
With Life Orb:
28 Atk vs 24 Def & 25 HP (75 Base Power): 9 - 11 (36.00% - 44.00%)
28 Atk vs 24 Def & 25 HP (102 Base Power): 11 - 14 (44.00% - 56.00%) - Average of 48.00%
The thing is, HP Fire Carvanha and ThunderPunch Meditite barely 2HKO their intended targets, meaning I can switch back out and save my pokemon for later after taking that first unexpected hit. Murkrow on the other hand, pretty much always OHKO's its targets with its "coverage" move of choice. HP Ice always OHKOs Gligar (unless its SpD Gligar, which still cant hurt Krow), while Heat Wave always OHKOs Komatana and Ferroseed. This means you literally have to guess which coverage move it has, or you will lose a pokemon. Its not like you can scout out its coverage moves, since taking any of its hits once is already hard enough...
You act as if you can simply tank a hit from Meditite with another Pokemon, especially since with Team Preview, it isn't
that hard to predict a Gligar / Misdreavus switch in or whatever, and then react accordingly.