The Amity Square is in the north of Hearthome City. Only "cute" Pokemon are allowed to enter into the park, this includes Pikachu, Psyduck, Skitty, Clefairy, Jigglypuff, Pachirisu, Drifloon, Buneary, Happiny, Shroomish, and Torchic. In Pokemon Platinum, however, more Pokemon were added to the list. These are Turtwig, Grotle, Torterra, Chimchar, Monferno, Infernape, Piplup, Prinplup, and Empoleon.
I think you can get items in amity square and make friends with your Pokemon
No one owns amity square. EDIT: This is in fact not at all true, the person who owns the Pokemon Mansion, you know him? Well he's the Owner of Amity Square.
sorry but no you can't find any Pokemon in amity square
there is nothing specific you need in Amity square. It is just there as something to do besides battle
Underground or in Amity Square (i think its in one of those old buildings at amity square)
no pichu cannot go in amity square but pikachu can so :p i reckon pichu is cute though
Amity Square.
It is in hearthome city
there isn't 1 lol
you can get it in herthome city in AMiTY SQUARE
It can be found in Amity Square by the pokémon.
You can find the TM Secret Power in Pokemon Diamond in the lower western part of Amity Square. It can be found roughly south of the man with the Pikachu.