1. Shellos :: Simply find him near the beach and talk to him. Once you do, by random chance you'll become either West or East Form of Shellos
NOTES: This is a guaranteed change, simple talk
2. Starly :: Find Staravia, then Sudowoodo. Talk to both upon seeing them, then go back to Staravia and It should ask if you want to become Starly.
NOTES: You have to go back and fourth between these 2 NPCs for a little bit.
3. Bidoof :: Find Bibarel's Parcel and return it to him.
NOTES: You get his Parcel from the Bronzong, South of the Beach Front.
4. Kricketot :: Find it in a tree in the Upper Cave Island (UCI)
NOTES: Pretty basic, just random chance
5. Budew :: Go into the Flower Forest, Find a Shiny Stone for Tiny Roselia and give it to her. NOTE: Only Grass types have access to the Flower Forest.
NOTES: Did you happen to see the random Rock/Pond near the center north of teh Flower Forest? Well just check the rock and after a while you'll have yourself a shiny stone. Also, Budew may be anywhere in (but not out of) the Flower Forest.
6. Cranidos :: Mine a Skull Fossil in the Underground Cave, then Find Rampardos and talk to him.
NOTES:Rampardos runs around so he could be anywhere.
7. Shieldon :: Mine an Armor Fossil in the Underground Cave, then Find Bastiodon and talk to him.
NOTES: Bastiodon also runs around so look around.
8. Burmy [Grass] :: Find a Burmy in the Trees of the Dark Forest
NOTES: This is another random chance action
9. Burmy [Sand] :: Find a Burmy in the Sands of the Dark Forest
NOTES:
10. Burmy [Trash] :: Find a Burmy in the Torn World
NOTES:
11. Aipom :: Find Aipom in the Safari Zone
NOTES: You need to be at least Lv15 and have 500 pd to get in. He is in the North East corner, You'll need Cut or Rock Climb to get him.
12. Misdreavous :: Get Dittos Package and give it to Mismagius at the entrance of the Flower Forest
NOTES: The 'Mysterious Pokemon' is a Ditto that used transform.
13. Mime JR :: Talk to the 3 Mime Jr's on Mimic Island for a while then talk to the shiny one.
NOTES: You'll Need surf to get here on your own or a Sky Ticket to fly here.
14. Chatot Talk to Chatot and tell him his Ability
NOTES: You can check Serebii.net for this.
15. Munchlax :: He is only available through Random Rare
16. Hippopotas :: Find him in the Safari Zone
NOTES: You need to be at least Lv15 and have 500 pd to get in. He is in the mid west side of the SZ.
17. Carnivine :: Run through tall grass and by random chance, you'll get a chance to become it.
NOTES: You need to know HM01 Cut for this to work
18. Finneon :: Find Finneon in the Safari Zone
NOTES: You need to be at least Lv15 and have 500 pd to get in. You need HM Surf to get to Finneon He is in the North West, in the river.
19. Sneasel :: Find Sneasel and get the Froslass's Razor Claw back
NOTES: You're actually looking for a Weavile because he used it on himself.
20. Magnemite :: Allow Magnemite to train on you in Mt Coronet
NOTES: You need to talk to the Safari Zone Man [in the SZ] once! Then get an Ultra Ball [Moss Rock] Then talk to the Safari Hunter, Who is past the water fall, in the far east of Sinnoh.
21. Magby :: Give the Magmar in the Southern Dark Forest a Magmarizer
NOTES: You must buy one from Lickilicky near the Beach Front.
22. Nosepass :: Find Nosepass then report back to Probopass, on Mt Coronet peak.
NOTES: Nosepass is in the Sinnoh Underground.
*Yanma:: Find him in the Safari Zone or in the Great Marsh
NOTES: This is a guaranteed find. You will become Yanma once you talk to it.
23. Uxie :: Find Uxie at the pond in the Oasis
NOTES: You need HM Surf/Waterfall or Rock Climb to reach the pond area.
24. Mesprit :: (See Uxie)
25. Azelf :: (See Uxie)
26. Dialga :: Find all 4 Time Gears [Oasis, Ocean, Forest and Mountain]
NOTES:
TG:Ocean is in the deepest part of the beach, You'll need to be a water type to go in.
TG:Forest is in the Dark Forest, Not the Flower Forest
TG:Mountain is accessible through the Underground cave.
TG:Oasis you need to fly there, using Staraptor.
27. Palkia :: (See Dialga)
28. Heatran :: Make your way through the Scorching Maze to the very end
NOTES: Fire types dont get burnt
29. Regigigas :: Find and touch each statue of 'Regirock', 'Regice', and 'Registeel'
NOTES: Rock is in the same cave as the Time Gear - Mountain
Steel is on Mimic Island, You'll need Rock Climb
Ice is on Ice Rock
30. Giratina :: You'll need the 4 Time Gears, as mentioned in the Dialga quest, and a 5th item called the 'Time Shield'
NOTES: Time Shield is hidden in the Crevice Garden. You need a Crevice to get in. (Get from Gliscor)
Giratina is in the Torn World, which has a portal hidden in the Oasis
31. Cresselia :: Trade Gliscor Star Dust and Sacred Ash for his Crevice to gain entry to the Crevice Garden
NOTES: Star Dust is on Ice Rock, Sacred Ash is in the Scorching Maze.
32. Manaphy :: Retrieve the Poke flute from Togekiss, then swim to the deepest part of the ocean and use it to wake Manaphy
NOTES: Manaphy is in the deepest part of the ocean. You must be a water type to get there. Recommended: Just become Shellos quick.
33. Darkrai :: Find the medicine for Gallade's deep slumber and give it to the Glameow
NOTES: The medicine is in the Underground Mining Cave (Not the Sinnoh Underground)
34. Shaymin :: Make your journey to the back meadow in the Flower Forest and Check the Spirit Leaf Trees for Shaymin
NOTES:You need a Glacedia Flower that only grows in the Crevice Garden. You must be a grass type to get into the Flower Forest.
35. Arceus :: Find the Dimensional Sword, Time Shield, and Space Aurora, then talk to the Arceus Enthusiast in the Torn World.
NOTES: N/A