Build and Runes
If you’re an AD champion, avoid getting hit by his Ground Slam, as it will significantly lower your attack speed.
Although you need good reaction time, it is very possible to Flash away from Malphite’s ultimate.
Try and spread out in team fights so Malphite can’t hit multiple targets with his ultimate.
Pick something ranged so you have a lot of space to play with, you will mostlikely dominate him with ranged abilities.