White clouds are far too big for 2.5 gallon tanks. 5 of them will really need a minimum of a 5 gallon tank to themselves.
Now if you can keep the temp of the 10 gallon tank to around 74F to 76F max, then I would suggest that you put the 5 white clouds there with a single male betta and 3 cories. That is it no more. That will be a healthy tank and with proper water changes (weekly) and possibly some live plants things will work out fine. Loose the cardinals in that tank though.
Now if you can keep the temp of the 10 gallon tank to around 74F to 76F max, then I would suggest that you put the 5 white clouds there with a single male betta and 3 cories. That is it no more. That will be a healthy tank and with proper water changes (weekly) and possibly some live plants things will work out fine. Loose the cardinals in that tank though.