2 player

havent played my psp for 6 months to a year now so im easing my way into this again. So i have a few things i dont remember.

i have games on my hard drive of the following but wanna know if i can play any of them 2 player

gb/gbc

gba

nes

snes

master system

mega drive

n64

ps1

Also i bought an 8 gb mem stick and a 2 gb stick. When puttin games on 2 gbstick from computer, it stopped and now my pc andpsp wil not recognise the stick.
ive got games on the 8 gig and it was going good but then same thing happened. i assumed id have to format them but cos it aint recognisable on either wondered how. However b4 i tried te 8 gb on my pc i put it into a m8slaptop at work and it recognised it. Any idea y that would happen