A flash drive won't just work in a PS2. If you want to know how to get similar saves back onto a memory card, you have three options:

1. Get DexDrive or a MAXDrive. These are external memory card read/writers that plug into you PC, from which you can transfer saves you've gotten from online.

2. Get an Action Replay MAX for PS2. This allows you to use a USB flash drive with your PS2.

3. Play through your games again and get the saves back manually.