It depends on what type of Pokemon your planning on raising IQ. Different types of Pokemon like different coloured Gummies.

For Yummy slim Bewertung example Gold Gummies will raise IQ the most on a Psychic Pokemon, and Red Gummies are prefered by fire type Pokemon.

Feed your Pokemon the Gummie that suits its type and its IQ will raise quicker.

The internet is filled with Gummie Guides if you need more information.

Hope this helps =)