Okay, so I was about to use a violin for my next composition but I would have plans on using pizzicato and legato. But is it possible for one to notate pizzicato in some parts and then notate legato in the same piece, same instrument?
Absolutely; you just write a little marking to indicate to the performer when to switch between pizzicato and regular bowing. In the score, we use the call arco to signal that the performer should bow regularly.
It's similar with brass instruments: a composer tells them to use a mute, and then a composer tells them when to quit using the mute.
Note that arco is the default method of playing; when a piece begins, the performer assumes arco unless told otherwise.
In the given example, the first two beats are played pizzicato, the latter two beats played arco.
Edit: I was operating under the assumption that by legato you simply meant "not pizzicato." Thus in my example I only marked arco on beat 3. Typically, if a composer really wanted a smooth legato, they would slur the legato notes together; this slur indicates that the music should be played without a direction change in the bow. In short, if you're writing for violin, make sure you have a grasp on all of their different articulation possibilities and the markings for them. An instrumentation/orchestration book is a great resource for this, and there are also several places online that you can find with a quick Internet search.
You probably don't mean "legato" as much as you mean "arco" (namely bowed as opposed to plucked).
Yes, using pizzicato and arco next to each other is quite possible as violinists don't necessarily put aside the bow when doing pizzicato.
Paganini even combines bowing with simultaneous left-hand pizzicato (of course, this needs careful consideration of physical limitations so it does not make much sense for non-playing composers to try those antics).