They don't like a lot of current so you would need to make sure that there is an area of quiet water for him to stay in. You didn't mention what kind of filtration you have so you will have to figure out if what you have can work for the betta's needs.

If you think it might work you can put him in with the other fish and keep an eye on him. If signs of trouble come along, just switch him back to his old home.

Hello, i had a similar issue. I felt bad for my old betta all alone and in a bowl. I put him in with 3 glow fish, 1 pleco (suckerfish) and two black mollies. The glo fish did really well with him, but the mollies did not. He also didn't like all the noise of the air bubbler. He passed away. The signs i saw before he passed were: He would hide a lot. He would sink to the bottom and only come up for air. He eventually became very lethargic as well. I should have caught it sooner, maybe i could have saved him..but i didn't recognize that this behavior was a warning. Any ways, like the last post-er said, keep an eye on him. Some bettas do enjoy company...they're all different from what i've seen.
good luck!