sorry for replying late.
there has been a ds emu for psp (by 物置 NekoMiMi):http://nekomimi.cafe.coocan.jp/dev/CatDS/DeSmuME20070725.zipInstalling: (didnt write this)Here’s a guide on how to install DeSmuME, of course you must have a homebrew-capable PSP.
* Move the 150 folder contained in the archive to GAME or GAME150 on your memory stick.
* Download any DS homebrew game, GeoWars for example.
* Rename the game’s NDS file to test.nds
* Move test.nds to the 150 folder.
* Navigate to the Game menu on your PSP and start the emulator. The game will load automatically.
but the games are limited, theyre making a way to use the touchscreen
so heres the game ready to play so far:
GAMES: (not written by me)BLUE = LOADS
RED = DOESNT LOAD
DS Commercial Games
Advance Wars Dual Strike
Asphalt Urban GT
Bomberman Touch
Castlevania Portrait of Ruin
Chokkan Hitofude
Cool 104 Joker and Setline
Daigasso Band Brothers
Deal or no deal
Diddy Kong Racing DS
Dragonball Z Supersonic Warriors 2
Electroplankton
Final fantasy III
Goldeneye Rogue Agent
Guru Guru Nagetto
hanjuku eiyuu ds egg monster heroes
Kenshui tendo dokuta
Kirby Canvas Curse
Kirby Squeak Squad
Legend of Zelda Phantom Hourglass
Lunar Dragon Song
Mario & Luigi ds
Mario Hoops: 3 on 3
Mario Kart DS
Mario Slam Basketball
Mario vs. donkey kong 2
Megaman ZX
Meteos
Metroid Prime Hunters
Mr. Driller Drill Spirits
Need For Speed Underground 2
New Super Mario bros.
Pac Pix
Ping Pals
Phoenix Wright
Pokemon Dash
Pokemon Diamond
Pokemon Pearl
Pokemon Ranger
Pokemon Trozei
Rayman DS - Raving Rabbids
Robots
Sonic Rush
Space Invaders DS
Spiderman 2
Sprung the dating game
Super Mario 64 DS
Super Princess Peach
The urbz sims in the city
WarioWare Touched
Yoshi Island 2 DS
Yoshi Touch and Go
Zoo Keeper
DS HOMEBREW
GeoWars
iPodClone
Text Tic Tac Toe
DS DEMOS
Metroid Prime Hunters Demo Video
Table Hockey
Tetris Demo
Zelda Twilight Princess Movie Trailer
Notes:[b]PSP_CTRL_CIRCLE = A
PSP_CTRL_CROSS = B
PSP_CTRL_SELECT = Select
PSP_CTRL_START = Start
PSP_CTRL_DOWN = Right
PSP_CTRL_UP = Left
PSP_CTRL_RIGHT = Up
PSP_CTRL_LEFT = Down
PSP_CTRL_RTRIGGER = R / toggle touch
PSP_CTRL_LTRIGGER = L
PSP_CTRL_TRIANGLE = X
PSP_CTRL_SQUARE = Y
Now ofcourse, their is also a pc ds emulator its called No$Gba u can look it up in google
ummm... download it, it runs every rom

hope this helps