If you land on an ally space, but no ally is available, what happens?

If you land on an ally space or use an ally phone, but all the available characters are already taken by other players, what happens?

Example: If all 4 players have 3 allies each (with no unlockable characters unlocked) and I land on an ally space, what happens?

My guess is that if fizzes out, and nothing happens, but I can't know without having the game where you always land on allies spaces. Got close once (there were only 2-3 allies left) but never got to a game where all allies were taken.

Solution 1:

Caps at 4, if you land on the space after that, the game tells you that you have enough allies.

More info: If you land on an Ally Space, your ally list is full but there is one available, you can boot an ally out of your party and select a new one.