In Dr Mario World on the iOS app, I chose Dr Mario after clearing level 10, between Dr Mario, Dr Peach, and Dr Bowser. However I want to change my mind and choose Dr Bowser, or preferably choose freely between them when I want. Is it possible to rechoose my Doctor?
After level 20 you will unlock the ability to staff new characters. There are a total of 13 doctors (including mario, bowser, and peach) and 36 assistants.
You can then choose which one of your unlocked doctors you use, and you can use up to 2 assistants.
To unlock a new character you have to pay 4000 coins, 40 diamonds, or 1 staffing ticket (or whatever they are called). This is random and you can get the same character multiple times, which would upgrade that character, rather than unlocking a new one.
The chance to get dr. bowser is 1.53% on each try. It will take about 65 tries on average to unlock dr. bowser, which would cost about 260000 coins, or 2600 diamonds. You may get doctor bowser after a lot more tries, or much earlier, it is random.
A fully upgraded character will be removed from the pool of characters that you can get. If all characters are fully upgraded, you will no longer be able to use the staffing feature until more characters, or upgrade levels are added.
King Bob-omb and Banzai Bill are not obtainable through staffing, you can however unlock them in versus mode if you are tier 3+ for King Bob-omb, or tier 5 for Banzai bill.