250 litres will not really be adequate for a minimum of 6 of each of your listed fish types although am unfamiliar with Leopard Botia, is this like a Polka Dot Loach?
If so, then its still a no, 250 litre is still not enough IMO, but exact numbers am not too sure, someone on this forum for sure can give you more accurate stocking numbers. (this is dependant on the dimensions of your planned tank)
Removing the Leopard Botias ( if are Polka Dot Loach) may be ok but still pretty well fully stocked though and would need to do at least 35% water changes minimum per week, in a 250 litre tank, thats a lot of buckets!!
Do note if you are not already aware Giant Danios may be jumpers, so ensure you have a lid on your tank.
Also Platys, would say 1 male to at least 2 females, ratio 1:2+ (M:F) to avoid potential problems.
Have to say am still pretty much a newbie so don't take my word for this, this is just my opinion.
Wait for someone with more experience to give a better answer!