Blazekid3 said:
why some roms need patch to save ??? they save but after i play them again it says data is corupted
That sounds like the rom was SRAM patched with GBATA or some other old SRAM patcher. GBA games that use 128KB saves (like SMB3 and Pokeyman) actually hold two copies of the save data. GBATA patches them to use 64KB saves (because this is what old GBA flashcarts supported) which is enough to hold one of the two saves and save properly, but because one of the saves is missing you get the corrupt data error every time the game starts, even though it still loads your save.
Try it with a clean rom, or just deal with the error message.