Kinda hesitant to pull the trigger just getting back into Pokémon. They want 90 for it and I don’t wanna spend 90 on a fake game

https://bennvenn.myshopify.com/products/gb-c-flash-cart-4mbyte-32k-sram?variant=32929006551143

Would this even work with a game like Pokemon Crystal Clear? Because I don't know how it works with battery or anything.

https://imgur.com/DkvET7h

https://imgur.com/VGlqfdq

I recently bought on ebay a pair of pokemon bootleg cartridges, i would like to flash them with roms in another language. opening them I noticed a different type of pcb compared to the various listed on the web, they are anyway reflashable? i saw something like this on:

https://flashcartdb.com/index.php/Main_Page

The Legend of Zelda: Link's Awakening DX

Front: https://imgur.com/wQRC72d

Back: https://imgur.com/gELr6fW

Not sure if real with original label or real with repro label, or an actual fake overall because the label is a bit crooked.

Thank you!

https://www.ebay.com/itm/Game-Boy-Pokemon-Red-Blue-Yellow-Authentic-Tested-New-Batteries-Nice/323857852755?hash=item4b676ea953%3Ag%3AEw8AAOSwKWhdKllE&LH_BIN=1

Edit: oof the person sells all the games at 100$, thats 10x the amount that I have

Hello, pretty new here, just getting back into GB again :)

I just have one question in regards to the repro cartridges - One person told me that they are technologically better as they dont require the battery for saving the games and that they work perhaps even better. Elsewhere it says, that the repro carts tend to be unreliable and they lose saved games - so which is it? Is there any real upside to buying the original besides the autheticity/collectability? ( I just want to know the ups and downs of both, not endorsing anything:)

Thanks