Many have already stated ones I'm re-stating, but I have a few more:
"I am the flame that lights the night: the flame that shatters the darkness. I am a flaming Moltres...mwhahahahaha!!!!" -- James
"That Magnemite's following Pikachu...like a streaker or something." "Ash, you mean a stalker!" -- Ash; Brock
"Hey, I know! I'll use my trusty frying pan...as a drying pan!" -- Brock
"Don't worry Brock, you'll find plenty of other girls to reject you." -- Ash
"It pays to have protection!" -- Team Rocket; "Having a Wailord of a Time!"
"EEEE!!! He took my parasol!" -- James
"Don't mention that name!" -- Brock
"The human sacrificed himself, to save the Pokemon. I pitted them against each other, but not until they set aside their differences did I see the true power they all share deep inside. I see now that the circumstances of one's birth are irrelevant; it is what you do with the gift of life that determines who you are." -- Mewtwo
"Thousands are inside rooting for Ash, while Team Rocket is outside rooting through trash!" -- Jessie
"Ash climbs just like a Mankey." "I think he just evolved into a Primeape!" -- Misty; Brock, M04
"We do have a lot in common. The same air, the same Earth, the same sky.
Maybe if we started looking at what's the same instead of always looking at what's different...well, who knows?" -- Meowth