Blitzcrank vs Braum

Fire Rocket Grab (Q) from a brush or a side angle: it grabs the first enemy hit, so you need a line without minions.

After a successful grab, cast Power Fist (E) right away: your next auto knocks the target into the air and deals double damage.

Sometimes engage without a grab: rush in with Overdrive (W), knock your target into the air with Power Fist (E), and save Rocket Grab (Q) for when they Flash away.

Use Mana Barrier (passive) to bait: at low health you get a shield based on your mana, enough to make a kill look easy.

In teamfights, save Rocket Grab (Q) for their carry and wait for them out of vision: grabbing them before the fight starts often decides it.

Back off when you have Concussive Blows (passive) stacks on you: his allies' autos add stacks too, and the 4th stuns you.

Catch him when he's far from his allies: Stand Behind Me (W) only leaps to an ally, minions included, and without one nearby he has no dash.

Don't shoot into Unbreakable (E): it intercepts your projectiles. Go around it, use AoE spells, or wait for him to lower his shield.

Don't line up with your allies in front of him when he has Glacial Fissure (R): it hits every enemy along its line and around him with a knock-up.