What type of degrees are important to become a scientist ?

To become a scientist, you do not need any degree. You just need to do brilliant researches. But if you are talking about particular scientist job, then you must be a Ph.D holder.

Technically speaking, no degree is mandated to become a scientist, you just need to have a brilliant approach towards things. Practically, a Ph.D degree is needed and even post Doctorate is important if you want to be recognised as a scientist.