26 letters( the English alphabet) and a (!) and a (?)
According to Serebii.net there are 493 Pokemon in Soul Silver.
Their are 434 pokemon in soul silver according to the strategy guide.
over 9000
256 pokemon. But all together 493.
Once
there are only 8 rare Pokemon in soul silver (articuno,zapdose,lugia,entay,hoho,rioku,moltress,suikune)
you can fight him as many times as you want
It's an endless amount of Shiny Pokemon, but it is really hard to get or find them.
A thousand!
There are many Pokemon found on Mt. Silver of various levels around level 40 to level 50.
You can have up to six Pokemon in your party at one time, as usual. But in terms of how many you can actually possess, that would be all of them :)
only 300 are allowed in the games