Pocket Tree Friends

Pocket Tree Friends (also known as Poke-Tree Friends) is a HTF-Pokemon crossover fangame where characters from Happy Tree Friends (including fan characters) act and behave like the Pokemon creatures.

Gameplay
The gameplay is pretty much the same like the main Pokemon games. You start the game as a trainer whose gender can be chosen by yourself, which then gets his/her starter Pokemon (in this game's case, tree friend) and must set off to beat all 8 gyms in the region before challenging the Elite Four and the Champion.

Various other known Pokemon mechanics, like catching using Pokeballs, are also present in this game.