I have two theories about Dale's personality.  The first one is that Dale
is a total goof off.  Thus making him a pain in the side of the Rangers.  
The second is that Dale is smart, but he just doesn't have all of his 
marbles organized correctly.  Whichever theory is true, the fact is Dale has
proven his worth countless times in many of the Rangers' cases.  One of his
strong points might be his tendency to be unpredictable, making it hard for
villains to guess what he will do next. 
     If there is one Ranger that Dale is definitely a pain in the side of, 
that Ranger would have to be Chip.  Time and time again, Dale and Chip get
into arguments that are almost totally ridiculous.  For instance, getting 
into a fight over who gets to sit in the front seat of a Ranger vehicle 
or plane with Gadget.