Pichu evolves (in all the games) once it reaches full happiness
A vileplume can't envovle into bellosom u must envovle it when it is a gloom use a sun stone on gloom and it will envovle into bellosom.
Usually somewhere after lv. 20.
it evolves at level 36
Dragonair evolves from Dragonite starting at level 55.
i dont think any pokemon that are legendary envovle in platinum pearl and dimond.
Any level at max friendship. Example: Pichu is at Level 99. (Probably not happening.) and it's at max friendship, it can evolve once it's leveled up at max friendship... Even at an extremely high level like 100.
Clefairy can evolve at any level because it evolves into Clefable by using a Moon Stone on it.
pichu
pokemon breeder in route 210 he has pichu, happiny,pikachu
No, that is only avilable for Pokemon HeartGold and SoulSilver. But a Shiny Pichu can be obtained in any game with Pichu in it, but it's really hard to find.
Maxed out happiness
tropy garden,and many more!you can also get a baby pichu by getting a egg from a pikachu or raichu in the daycare. by:poke-expert rookie pearl