CaiYan

B+ for Ditto + Interesting ability of Imposter. It can makes the game fun enough by reading opponent's moves for you and help you experience DEMON or MEGA pokemons, or leaders' custom moves. + Any Ditto with an Imposter is great. You needn't select moves and train EVs for it. It really help saving time, but be sure to keep a high level. + A very great solution of Amber. Use a Flash-Fire Helping Hand Growlith (obtainable in Gearen Helping Center) and an Imposter Ditto(on the right position) can Easily beat him with his Typhlosion. + Will be useful when you need breeding. + Only in Rejuvenation, a Ditto always moves faster than its target if it transformed. - Relatively late (gain access to Tarajuma Shore). - Embarrasing when meet some opponents. Swoobat from B+ to A + Double-Team increases 2 levels of Evasion makes it very easy to setup. + Although defenses are low, it is not difficult to endure special moves by Calm Mind. + You can get Stored Power Natu early, so it is easy to get a Stored Power Swoobat although it's an Egg Move. + Stored Power is very easy to sweep Gyms after Calm Mind, Double-Team and Call (2 levels of accuracy). - Only ONE X-Defense can be picked up. So use it carefully!

Ditto always moves faster after transforming. Ditto transforms into fainted pokemons through its ability, if it is sent in when opponents have only 1 pokemon left in double battles. While using Ditto some other problem occurs. If both side use Sucker Punch, both can deal damage. While the latter one should fail.