All you need to know about the Daleks is they basically view themselves as superior beings to all lifeforms, their entire purpose in life is to exterminate all non-Dalek life, they even go so far as to create a time bubble only they exist in order to destroy the entire universe and live in total isolation. It is easy to role play a Dalek because they are all insane. The people on the show are just fodder for the Daleks and the Doctor is a Time Lord, basically an alien who bends the rules of time and space for his own amusement. The Master is an evil Time Lord whose motivation is hard to explain. All you need to know is the master and the doctor are immortal and travel in time and wage a war against the Daleks called the Time War that ends in mutual extinction of both races.
Pokepal appears to be basing his story off the classic Doctor Who, all of which are available on Hulu Plus, many are available on Netflix. If you prefer the NEW series then the episodes to watch, just to get a feel for what a Dalek is, would be Season 1 Dalek. Watch that episode or the Season two part ending Bad Wolf, those three episodes give you all you need to know about Daleks. Also they are supposed to be genetically engineered geniuses. Davros is their creator. They were the Doctors first enemies on the show and appear to be his arch nemesis. The Master is an enemy of sorts but also a friend to the doctor he is harder to explain. Daleks have ONE purpose and that is to KILL anything that is not a Dalek, or any Dalek that does not look, act and talk like them. The robot suits are just armor the actual Dalek is a tiny little ugly as fyck one eyed alien.