Simplify the following text for a Grade 6 native English-speaking person.
Original: Since 2005 MGA Entertainment has been involved in a lengthy legal dispute with Mattel over the rights to the Bratz design . Though Bratz dolls fared poorly at their May 2001 debut , their popularity increased the following Christmas .
Simplified: The toy company MGA Entertainment makes Bratz , and the first dolls were sold in 2001 .