Cell, Frieza and Raditz aint gonna have a hard time beating 100 dudes... Frieza regularly kills more than 100 strong dudes with ease, Cell wiped out the millitary (Full of more than 100 strong dudes)
Raditz... well he didnt beat 100 strong dudes but he told Goku to kill 100 dudes and he was...
They would all have to stand somewhat close to each other, Prime time to get Super Kamehameha/Double Sunday/Death Wave/All Cleared.
Also if they miss? Its over
Mewtwo is the best answer we have the most solid evidence for.
Nihilego through absorption became a trainer... so it at least understands how Pokeballs work and what to do with them.
Lucario? I don't think it would want to be a trainer
Zoroark could be a trainer though Illusion if it wanted...
All Pikachu have the same weight, despite how fat they look
Unless you have a specific Game Pikachu you want to use...
Since weight only differs in game... outside the games unless stated otherwise... all Pikachu weigh 13.2 lbs.
It would just boil down to whoever moves first.