I thinking about getting a flash card and doing flashme and I was wondering if I HAVE to use a pass card/ pass me
You just need a method to run DS code. This can be an already flashed DS, a passme/nopass with a GBA slot card that can be used for the DS (newer EZ4s can not), one of the other means that you don't really want to use for this, or a DS slot cart. Today most would use a DS slot cart to get it.
Flashme itself does not provide a terribly useful way to run code, certainly not commercial games. Its benefits are for most these days the option to not have the health and safety screen and the option to easily boot modified download play games. For any normal use you will want to get a DS slot flash cart which handles all the running of games, including modified ones, cheats, homebrew and more besides.
Brick protection is a big reason to install IMO, there have been trojans in the past which end up bricking consoles.
TC may want to get a card which also works on the 3DS and ntrboothax in case they ever get one and want to hack it.
Key phrase is in the past. They are so vanishingly rare these days that I thought I would skip it.
I do normally mention it in flashme topics but then end up having to do two or three more posts explaining how unlikely it all is and offering some assurances on the matter.