well since u can only have four pokemon to battle with maybe the fifth one is for a pokemon that can counter his team or a different part of his strategy just like having a sixth but he didnt feel like he should have another poke to prepare for the match and stuff cuz he knew his five could take...
let me see, it is a tie, between pikachu and pichu. i always liked pikachu because he was ashes pokemon and i always needed him to kill misty for me in red and blue version cuz i always had charmander. and i just found how he is in the show to be awesome. and than pichu because he is so cute:)...
ya it has happened to me i almost died when i couldnt release this one pokemon and couldnt figure out why, it was the only pokemon in my game to know dive. so i caught and gave another pokemon dive and i got to release it:)