ash gets cyndaquil at episode 143: Good 'Quil Hunting
Episode 454: Battling the Enemy Within is where Ash gets possessed by the dark spirit of Pokelantis.
Episode 13 after she catches buneary
In Pokemon Episode 308 May ans Max get kidnapped and tied up in a web. In Pokemon Episode 390 May gets tied up in rope and Ash gets kidnapped.
because he is secretly in love with ash
Dawn catches Buizel in the episode that is titled "Buizel Your Way Outta This."
Ash never caught Buizel. Dawn caught it but she traded her Buizel for his Aipom.
Ash's Buizel has not yet evolved, and is unlikely to do so in the near future as it is not part of his team presently. That said, it is still possible that it may evolve in a future episode.
it is leve
Yes.
The episode in which Ash gets the Rainbow Badge is called "Pokémon Scent-sation."
ash gets cyndaquil at episode 143: Good 'Quil Hunting
yes it does
Ash traded his aipom for Dawn's buizel
Ash catches Corphish in "Gone Corphishin'", 23rd episode of the Advanced Generation Series and 297th episode in the anime.
later on maybe never
It did not,and will never. (mostly)