Verified answer

Press the A button when in front of the tree on the right.

ok, there are i think 8 trick things, ring a bell, there are 8 gyms, to get him to do new tricks you need to beat the gyms, and once you beat the elite four, he gives you his final trick, i had to figure that out on my own, if for some reason this dosent work, i have no idea why, cause that is what i did

keeep ur eayes open u will see a shiny thing fopr like 1 second then prees A there and he will apear