"in 2000s yuvan has started the trend of youth based music"

Yuvan hasn't started any trend. Youth based music was given in early and mid 90's by ARR like Kadhalan, Thiruda Thiruda, Rangeela, Kadhal Desam. Even post 2000 the best youth based music was AE and Boys. Yuvan is not even poor man's ARR yet. The only trend post 2000 is Dapankuthu which is revived by VS.