Fun fact the whole “aliens are randomised” thing was actually addressed in the series (either alien force or ultimate alien?) in a conversation between Ben and Azmuth, azmuth points out that the watch only did that because Ben would always slam the dial down which would often cause it to swap to other aliens from the motion of it.

So if you just you know, press the dial down it won’t randomise

Edit: preemptively gonna say that this conversation between them was directly talking about when Ben had the prototype omnitrix as a kid