First line is more suiting for SkullMan, though CrashMan is built for defeating MegaMan too it's not like his sole reason why he exists, which is the case for SkullMan. CrashMan is loyal servant of Dr.Wily and goes with any mission, including defeating MegaMan, but any other will do. Usually docile he can go all psycho when things gets out of hand so in intros he is calm and after battle, especially when have low health, he can lose it and go all nuts with lines like "looks like you beyond repair now~ ahaha... Wahahahahahahaaaaa", "who's laughing now, eh? Ahahahahaaaa", etc.
Others are good. You may use those lines for intros if you want:
"You think I'm some knock-off, is that it? I'm all the power of Guts Man and Bomb Man combined, you little punk! Who are you to talk, Mr. Copy-powers-'cause-you-got-none?!"
―Crash Man, Mega Man (Archie Comics)
"Hey, hey, step aside, Magnet Man. It's time for Crash Man to finish this job with his Time Bombs."
―Crash Man, Episode 4: Mega-Pinocchio (yeah he had TimeBombs weapon in cartoon, you can freely exclude MagnetMan from phrase)
Rockman: Dr. Wily no Inbou - "Long live to the Wily empire!!"
Rockman World 2 - "I'm Dr. Wily's trusted confidant... Crash Man!!"
Cinco de Mayo