What type of ions are formed by transition elements?
As you also have heard them as Transition metals , so the word metal also suggests that they have the tendency of loosing electrons thus gaining a positive (+ve) charge and becoming a cation.
But they have variable charges or oxidation numbers. FOR e.g
IRON has symbol Fe
IT has two types of cations .
And similar is the case with other transition elements
So in the conclusion we can say they form cations and some of the transition elements have variable charges.