Legit question. I can't figure it out.
His ult ground pound combo nearly kills me and I'm stunned for so long after the ult that he gets at least one free AA on top of it. Then you can't even escape because of his Q.
How do you deal with him? Why is he allowed to have so much meat AND damage?
As a Malphite main, while yes banshees veil and qss are probably your most reliable way to give you a fighting chance, which, if a good Malphite sees you have that he will hold off on the as and ms debuff untill you blow it making it so your still screwed. In general however the most honest answer is as an adc, you dont deal with him. His meat is because he gets free armor from his w (30% extra at max rank) on top of needing little to no ap items due to poor scalings. If an enemy picked Malphite there are only a few reasons they did that. Reason 1. They see you as a threat and need a reliable way to deal with you. 2. They have a fantastic lane for him. Or 3. They have a wombo combo Malphite enables for the team. in general stick with your team, and watch him carefully, in a game with a Malphite, he is the one you should fear most out of laning phase.
Honestly, you deal with is by having a good support. Make sure you and your support are spaced out enough so he cant hit you both, and your support should be able to shield you/peel him. He is pretty frustrating though. Also, make sure if malph is going to be a problem, you get an early last whisper.
Stand farther away and make sure someone is ready to CC him when he lands. Itemize as you normally would, maybe with more priority on 
than normal. works really well too, despite only giving defensive stats.
Also, unless he builds significant AP his lategame burst isn't really that huge.
I just run the fk away
is good since her e can move her away from the ult thus avoiding the engage. Saving 
for it is also good. Both need good timing and vision.
Usually for champs lime malphite who look to engage with ults like his, you can watch his movements and learn when he will engage. As an adc, you should already be in the backline of teamfights which will help you avoid him well if he does try to engage, but if youre his soul target then banshees is your best bet
You don't. Your other lanes or team-members need to deal with him.
are his strongest lane-counters.
Everyone else has already answered most of what you need to know anyway.
Jinx is a good choice. Her long range rockets means malp will most likely have to flash R to get her. So he can't do it often. She can shred him with items and kite if he doesn't have R.
is an Anti to AD/AS reliant champs, the real way to deal with him is to buy a and keep out of his ult range. another solution is to his ult when you feel he is going to ult you. You have little time since it has alot of speed and range. Or have a 
black shield you. thats really counterplay to him playing as an ADC
