I have a toilet in my basement(below ground level, that I might replace in the future, but is loose. After a recent heavy rain, when we ran the washing machine, water came from the bottom of the toilet and flooded the basement floor. Would a plug in the drian hole solve this, or do I have to reseal it somehow?
Since the upstairs toilet drain fine, as well as the tub, I'm assuming it's not a big backup in the sewer, but how would I be sure?
Thanks you

Would a plug in the drian hole solve this, or do I have to reseal it somehow? No! You have a blockage in the drain line downstream from the toilet.

Since the upstairs toilet drain fine, as well as the tub, I'm assuming it's not a big backup in the sewer,
WRONG! It's just a partial clog at this time but unless it's snaked and the clog removed it will get worse and block the line completely. The fixtures above it will drain but will come up in the fixtures beneath them unless the line's snaked and cleared. Good luck, Tom