Reserving for Skyshade. Gimme a sec. (White right?)
Do you mind if I give you two?
Phobia the ___
Take Phobia the *any Pokemon which can evolve*. Phobia is afraid of so many things you can lose count of them:
Fear of Change - Phobia cannot evolve. 
Fear of Heights - Phobia cannot be in the party when you use Fly. 
Fear of Water - Phobia cannot be in the party when Surfing. (does not apply if Phobia was caught in water) 
Fear of Sharp Objects - No slash-based moves, e.g. Cut, Slash, X-Scissor. No STAB. 
Fear of Being Useless - Phobia must switch in every major battle (e.g. Gym Leader, Elite Four, N, Rival, etc.) 
Fear of Loneliness - Phobia must always be accompanied in the box by at least one other party member. 
Fear of the Dark - Phobia cannot be in the party when in caves. (does not apply if Phobia was caught in a cave) 
Fear of Being Unliked - Phobia's moves cannot be above 60BP. 
Fear of Foreigners - Phobia cannot attack other Pokemon which it does not share typing with. 
Fear of Being Left Out - Phobia's moves must all be known by other Pokemon on the party. 
Fear of Dying - Phobia must swap out when down to yellow or lower health. 
Fear of Disease - Phobia must always hold a Lum Berry. 
However, it learns to overcome its fears as it grows. When it reaches certain levels, it gains Anti-Phobic Points which it can use to offset some of its fears. the number of points needed to get rid of each fear is listed next to the fear, and the points it gains are as follows:
Level 13 - +2 points
Level 21 - +2 points
Level 42 - +3 points
Level 55 - +3 points
Level 75 - +5 points
There are also therapists in some cities; however they charge Pokes for treatment.
Castelia City - 150 000 Pokes / Point
Mistralton City - 294 000 Pokes / 2 Points
Opelucid City - 425 000 Pokes / 3 Points
If you want to use a therapist, go to the city with Phobia and toss goods equal to the cost.
Accursed the Yamask
Take Accursed the Yamask. Catch it on your first visit to the Desert Resort.
Once Accursed reaches Level 29, teach it Curse. It must use Curse on every opponent it meets. If it faints after using Curse (either from the opponent’s attack or from the half HP damage), note it down. If this counter reaches 4, it loses a move slot. Now pick any section of your bag besides your Key Items pouch, you may not use anything from that section any more. If the counter reaches 6, another move slot and bag section are lost. If it reaches 8, yet another move slot and bag section are lost. Finally, if it reaches 10, you lose a bag slot and your remaining Pokemon are all permanently under the effects of Taunt and Torment (unless it conflicts another Challange). To evolve into Cofagrigus, have 50 opponent Pokemon faint from the effects of curse. Accursed must solo one Gym Leader and one Elite Four member (of your choice).
If you reject this Challenge, the rest of your Pokemon are afflicted with Taunt and Torment (unless it conflicts another Challange).
If you just want one Challange though, ignore Accursed.