ya heres one for you ok its how to get tails in sonics level emreld beach go to the holtel pool and then go to the unbrella table next to the door in the gap u can get 2 now get as close as u can a fly tails should go thu the celling and you can hold foward a bit to get on the umbrella now fly trowds the beach and land on the sand if you do not enter it ther move close to the gate and ther tails at emreld beach and u can only go to the part wear the light house is and stuff and you will be sent back.

does anybody have a list of all the black market items

ok do you want to fight pirates then pick knuckles and go to casinopolis
and there should be a anchor on the floor next the nights pinball game and
climb up it there should be a pirarte ship with pirates on it if u want
to defeat the pirates go to the mystic ruins were bigs house is and
climb the wall and u should see some yellow gloves go back to casinopolis and go near a pirate and hold down the b button and when u are fully
red then BANG the pirate is dead there is captain pirate blackbeard deafeat him and you will get a surprise when you leave casinopolis tikal will be wait for u in the train staion talk to her and you will unlock either metal sonic in stead of gamma or supersonic instead of gamma to play with movies and not deafeating perfectchaos and see amy kiss sonic yuck.

I don't think there are any cheats for Sonic AdventureX... there may be some for the other built-in games, though.