How can I improve my cacti's condition?
I'm a beginner with everything plants and was given these cacti about 1-1.5yrs ago. They don't look very healthy and I'm not sure how to make their condition better.
I've kept them at my windowsill their whole life but recently learned the elongated and slanted shape (for reference, the 2 smaller cacti were tiny balls when they were bought) is due to lack of light, so I've recently been putting them outside for the day/most of the day. For their watering, I basically ignore them for a couple months and then give them a huge water, and repeat.
But now I'm wondering if they need re-potting, and/or to be in a larger pot. Do 5 cacti need a specific size pot to be together? My green thumb grandma suggested layering rocks and newspaper under the soil for drainage, that's why they're in a glass pot with no holes at the bottom. I'm open to any criticism, I'm very new to cactus care and would really appreciate any advice.