Well two would be the max. Also, I have a total of 3 pokes on my want list (in order of importance, Shiny Timid Riolu, Shiny Jolly Gligar, Shiny Impish Hippodown). Therefore I can make you a few choices:
1). If you can get me a Shiny Perfect Timid Riolu w/ Vacuum Wave by 12 PM ET on Saturday, then I am ok with a 2:1 trade.
2). If you can't get me the shiny perfect Timid Riolu w/ Vacuum Wave by then, you have to offer me a second pokemon from the list (Gligar w/ sand veil or Hippodown w/ slack off). Thus it would be a 1:1 trade.
I will be sending you EV'd versions of both. If you don't want the EV'd version for Darkai, then please lemme know before we trade.