Where are the guys in Pokemon platinum that give poketch apps?

You're likely thinking of the Poketch App Trainers in Pokémon Platinum. They're not actually guys, but rather a group of people who give you different Poketch apps throughout the game. You can find them in the following locations:

* Jubilife City: The first Poketch App Trainer is found in the Jubilife City Poketch Shop, near the entrance to the shop. They will give you the Clock App.

* Eterna City: This Poketch App Trainer is located in the Eterna City Department Store, on the second floor in the "Men's Wear" section. They will give you the Calculator App.

* Veilstone City: You'll find this Poketch App Trainer in the Veilstone City Department Store, on the second floor in the "Women's Wear" section. They will give you the Style App.

* Pastoria City: This Poketch App Trainer is located in the Pastoria City Department Store, on the second floor in the "Toys" section. They will give you the Steps App.

These are the main Poketch App Trainers you'll encounter in Pokémon Platinum. There are other Poketch Apps you can acquire throughout the game, but you'll need to find them through other means, such as completing events or interacting with specific characters.