a rather colorfull fellow isn't he? once again, Ike down there infornt of the colossus for comparison.
As i mentiond this colossus is rather tricky, since while you defeat him a section of him falls off and he gets faster. Infact when each section is "killed" Ike there falls down with the segment and has to climb back up
once only the main part of the colossus remains, Ike must climb the spear the colossus is holding since the main and real body of the colussus is so smooth there are no real hand holds.

the trick to geting up the staff is to wait for the colossus to slam it, bottom down into the ground while attacking from the air