Well, to answer your ASB questions...
The shiny rule never really existed so yea, add as many shiny as you want to.
Also, when you level up, you get 3 extra squad slots and if you want to add a dratini. Pokemon do not have level. Those are the trainer level so your dratini will start at level 1 and then, you'll have to fight a level up match which is just like a normal match. So yea, that's basically it. Let me know if you have more questions, I'll be glad to help.