Blitzcrank is a high pressure support who is infamous in lower elo's, and has a high amount of pick potential. With his abilites Overdrive, Rocket Grab and Power Fist, he has a combo that can lead to the death of almost any squishy in the game, considering he has sufficient followup. These abilities allow Blitzcranks roaming game to be strong, when his team is looking for picks or he's looking for a lane to gank and makes his early game among one of the best in the game in terms of solo que supports.
Passive – Mana Barrier
When Blitzcrank receives damage which brings him below 20% maximum health, he shields himself for 50% of his current mana for up to 10 seconds.
Q – Rocket Grab
Blitzcrank fires his right hand in the target direction, Airborne icon pulling the first enemy hit to him, stunning them for 0.5 seconds, and dealing magic damage.
W – Overdrive
Blitzcrank puts himself into overdrive, gaining bonus attack speed for 5 seconds and bonus movement speed that decays to 10% over the duration.
When Overdrive ends, Blitzcrank is slowed by 30% for 1.5 seconds.
E – Power Fist
Blitzcrank's next basic attack within 5 seconds deals 100% AD bonus physical damage and Airborne icon knocks up his target for 1 second.
Power Fist resets Blitzcrank's autoattack timer.
R – Static Field
PASSIVE: While Static Field is not on cooldown, Blitzcrank fires a lightning bolt at a random nearby visible enemy every 2.5 seconds, dealing magic damage.
ACTIVE: Blitzcrank detonates his static field, dealing magic damage to nearby enemies and Silence icon silencing them for 0.5 seconds.
Blitzcrank lives and dies on his Q. If he misses it, he has to sit through it's long cooldown, and when it's down, he's just another melee support. A really bad one at that, with only 'Power Fist' for catches or peeling. You can harass him endlessly as long as you play around his Q's cooldown.
If Blitzcrank fails to land his grab on a priority target in a grouping scenario, his team is far weaker, given the fact that most of Blitzcranks utility lies in his pull. The only thing he might offer is the static field, but the damage isn't high and the 0.5 second silence, while good, won't likely be game changing in that situation, with your backline out of range. Not to mention that after he uses it, the entire fight is a 4v5. Fight when his pull is down.
Wards are key to preventing Blitzcrank from snowballing lanes early. As the game goes on, the threat a long Blitzcrank poses is lessened, but early, the mitigation of his pressure via vision is a neccessity. Ward the river religiously as the mid laner, and keep eyes on the blue buff to make sure your team can pick off Blitzcrank in that situation.
She can just Black Shield the Rocket Grab, and if you pull her in the midgame she's just going to Soul Shackles the entire enemy team and survive because of her Zhonyas and then they're going to lose the teamfight. She just counters him really hard in both laning and teamfights, and makes it a bad time for him.
She's better at fighting. If Blitz pulls her, she'll ult his team. If Blitz pulls her in lane, she'll ult his carry. She'll just counter-engage every single time, and because she's made of CC, she'll do it better than Blitz can. Even in the case that she doesn't have her ult, she'll probably just dive in with the pulled target, especially if it's remotely tanky. There's no point at which Blitzcrank outdoes her.
Ezreal hits E, and even if the hook lands, he's going to complete the shift and be safe. He also builds CDR and mana, and his Q reduces his abilities cooldowns, so he can just keep being safe.
Hit E, deny the pull, there's no engage from Blitzcrank. She gains mana back, which gains lane presence and the potency of her push and poke. Even if he misses the pull and you burn the spell shield, he still doesn't have the pull, and is now vulnerable. She can also help his team run him down upon a spotted roam or invade.
Being a support he usually doesn't build damaging items, what's important is the wards. You need wards to ensure that he doesn't successfully gank your lanes early and snowball the game for his team. It's possible that a Mikaels can be justified, but by the time a support can afford one, if a Blitz pulls a squishy, they're typically dead before it matters anyway, and if he pulls a tank, it's a tank and it'll survive long enough to get it's CC off typically.