What kind of pellets do you use?
I personally like the Omega one betta pellets.
Also what size tank is he in and is the tank heated?
Bettas do best in warmer water around 80°F.
Good food, good size tank. I'd probably bump up the temp to 26 degrees Celsius as 25 is the very low end for a comfortable environment. Sounds like he's good to go as far as that goes.
Cardinal tetras should be fine the neons Cardinal Tetris should be fine the neons would be questionable. If you could exchange them for more Cardinals that would be better.What about my neon and cardinal tetras? Would they be ok at that temperature?