Dialga Because its a steel AND a dragon type,IN Pmd 2 & 3 It has a Major role,Its domain is a living beating tower,that keeps time going!,its domain is very hard to reach,Theres rainbows (rainbow starship)involved with it :D,its signature move looks Cool and makes sense,It has its own version...,Its got an evil persona as well as a good one in pmd 2 and 3,it can learn many different types of moves.So,thats why dialga is my faveorite before giratina and palkia. Oh and water types are my faverite types of pokemon,but dialgas one of a few exceptions (: