Is black the highest trainer card on Pokemon pearl?

No, black is not the highest trainer card in Pokémon Pearl. There are actually two levels above black:

* Rainbow: This is the highest level trainer card and is awarded for completing the National Pokédex.

* Gold: This is the second highest level trainer card and is awarded for completing the Sinnoh Pokédex.

So while black is a high level card, it is not the highest in Pokémon Pearl.