Well I have tried out loads of solutions and finally found out!I found out that the colour of your berry will be the same colour as the type your looking for.Like say if you wanted a blue pokeblock,mix a oran berry and there you go you have a blue pokeblock because a oran berry is blue so it would do a blue pokeblock.
Note:This doesn't work with all berrys.
Note:This doesn't work with all berrys.