This was definitely one excellent episode for the series.
Some great stuff from Gon's attacks to the friendship shown between him and Killua. They did a nice job hinting how badly Killua was hurting from those attacks, but in the end they are going to finish this fight together. Gon has certainly powered himself up through all that training.
Maybe favorite moment though was Killua's reaction when Gon said it had to be him that held the ball
.