This question already has an answer here:
I'm 20 years old now sooo I was probably watching this cartoon in mid 2000s. Basically these kids would enter a virtual world through these body portals and fight virtual monsters using special abilities that they received when they entered.
I remember they could be injured a certain number of times while in the virtual world but they had like a mission to complete. One of the kids turned into a cat like character. Then when they wanted to leave the virtual world, they found a tower that had like a target on it and they went inside and jumped off the platform.