- No. The only thing different about Shinies is their appearance; they are no stronger and no weaker.
In Generation 2, however, since Shininess was determined by IVs, Shiny Pokemon were forced to have certain IVs, which can have a detrimental effect if you want perfect IVs.
- There are reasons to use every type. Although Grass has a high number of weaknesses, it packs key resistances to common Electric and Ground moves like Thunderbolt and Earthquake. Grass is also a good defensive typing; being super effective on three types isn't bad! Dragon is only super effective on itself and Normal hits nothing super effectively, for example.
Also, if you have two questions, post them separately so we can vote questions properly.