Might need to save and quit more than once. Eventually, when Duskull appears just inside the main doors of the Haunted House, he will challenge you to a Chase.
You can't befriend him when he is at the gates of the Haunted Zone; or near the Piano in the Haunted House.
In the Beach Zone ,not that close to the Drifblim Stop
You get him by getting all the bonuses for empolions attraction
After you use the magical watering can, Belossom will want a bouquet of flowers. Go behind the Drifblim stop and bring the flowers to her.
you usually have to look for bubbles at the top of the zone keepers head but if you already been there,you can talk to drifblim and he will take you there.
You need to have all the pokemon in absols hurdle bounce to achieve the bonus
im pretty sure you have to make friends with chimchar, i don't remember if its automatically there.
Buneary
make sure you talk to everyone in the lavazone,cavernzone,icebergzone,beachzonehauntedzone,meadow zone.
In the Flower Zone, if you walk behind the Drifblim Post, towards the edge of the cliff (you won't fall off, don't worry,) you'll see a little white bundle. That is your bouquet. Best of luck. - Spiffi :3
you can become its friend but you cannot use it sorry
it is Emolga she is a cute bat pokemon its true
Get all the bonuses in Tangrowth's Swing Along.