Drifblim is a Ghost and Flying type pokemon.
Drifloon (the pre-evolved form) evolves into Drifblim. Drifblim doesn't evolve into anything. Drifloon and Drifblim are both psychic/ghost-type pokemon.
Drifblim is #426 in the national pokedex, and it is a Ghost-Flying type Pokemon.
Drifloon is the pre-evolved form of Drifblim.
Yes, Drifblim evolves into Drifloon.
Fighting Pokemon
I think you are referring to a drifloon or a drifblim. Drifloon is a ghost/flyig Pokemon and so is it's evolution drifblim. I might be mistaken, you might also be reffering to jigglypuff, written as the "balloon" Pokemon but considerng you said Diamond, I think you mean the Drifloon.
The Stage 1 version of Drifblim in Diamond is Drifloon.
drifloon
Go to Valley WindWorks on a Friday and Drifloon will be there. Catch it, then level it up into Drifblim.
Drifblim, Gengar, and Mismagius
By using a ghost or a dark type move (super effective). Fighting against Drifblim: don't and i repeat, DON'T, use a physical attack on Drifblim. You will suffer from Drifblim's Ability. The ability is called Aftermath or Unburden. It is when the attacking Pokemon uses a physical move and takes a recoiled dmg
Drifloon is a ghost and flying type Pokemon that resembles a balloon. It evolves into Drifblim in the games at level 28.