No. Vegeta will blow up the planet. He can do this at Super Sayian 1. If you want to see the brutality Goku, Vegeta, Gohan, and Piccolo go through then click on the very top link in my signiture. They go through so much. Goku can fly faster then the speed of light at Super Sayian 4. Same with Vegeta. It`ll take some time to charge the energy but they can blow up the universe at Super Sayian 4. The link on the very top only shows Super Sayian 1, 2, and 3. If Goku and Vegeta fuse they become Super Sayian 4 Gogeta an indestructible force by far. Nothing was able to hurt them. Even the strongest enemy in DBGT. I`ll put more links. Ok here are all the links with DBZ and DBGT excluding the Kirby one.
If you still want to challenge Goku or Vegeta your going to have to back up your reasons even farther. Unless they can push a condensed negative karma ball and turn it into positive energy without dying then come challenge the Sayians. Condense means to group together. The negative karma ball did not get weaker, it got stronger.
I will not be availible today. Oh and I agree. Knuckles should have been in Brawl. Hes may favorite Sonic character.