Old Gameboy color, Gameboy advance, and Pokemon blue cartridge

I have a Gameboy color who’s buttons finally stopped working. I have a Gameboy advance that’s a bit wonky with the batteries now (back is missing) and my Pokemon blue cartridge took a dump lol it still remembers my save file somehow, but as soon as I enter battle or go to view my Pokemon, it glitches out and makes some god awful noises lol and I have a gold cartridge with a dead battery, a long with a ruby and emerald with dead batteries. I wanted to fix myself, but seeing what’s all involved, I’m too scared I’ll break something, so I was wondering the best recommendation to get all of the above fixed/repaired? I don’t ever recall water damage to anything, maybe some poor storage, but all issues just happened in the last 9ish months.

Thanks so much!