Kled's Ultimate Is Too Toxic.

pray to God

You can cut short how long he's going by "bodyblocking" it. It magnetizes to the closest/first enemy champion he meets while rolling along. Thus (if you're a tank or at least somewhat healthy), you can get closer to him to stop him from going any further and protect the ADC or whoever it was he was targeting both.

A strong counter is Nami, as shown many times her ultimate cripples his speed buff to allies and separates them easily.