It was pouring with rain. or it was raining cats and dogs.

中国有两句成语叫，瓢泼大雨，倾盆大雨。就是说，雨如同从盆里泼水一样泼出去，倒下去。就是说，形容雨势之急，雨量之大

泼 and 倒 are two actions. 倒 is pour，such as 倒水=pour water。泼 is splash，泼水= splash water。In your sentence, 像泼，像倒 can be described as 像泼水，像倒水 which means the rain is heavy.

（雨）像泼（的水）=the rain is just like sprinkling water （雨）像倒（的水）=the rain is just like pouring water 像means "look like". 泼and倒 are verbs here