Have you ever...

[GreatGonzales106]

...played through a Pokémon game and only trained your starter?

I used to do that every time, until I got Pearl.

[Gwen Khan]

when I first started with Red so many years ago

[darkmario]

 I beat diamond twice,I did that the second time.My chimp car was uber  :)

I only caught hm slaves.

[ThePowerOfOne]

I used to do that when I was younger. Its too much of a pain in the ass to raise any others until after you beat the game.

[JrDude]

I never did that, I still do this dumb thing though: Train the lowest level in the party, and when they level up, move up to the next lowest leveled pokémon, if 2 are at the same level, then train the one with lower HP first, if they have the same HP, train the one with lower stats. If all pokémon in party are the same level, my starter must be last in the party because he is "best".
IDK why, but it always worked out for me.

[Level_9_Chao]

Yeah, I always made my starter good and just kept catching the local wild Pokemon of similar level to add to my team. Did this until mid-GBA era.

[tibar21]

I've always done it and i'm still having to train my other pokemon in pearl right now. I'm gonna try to kill the habit for platinum.

[Lotos]

I never did that, I still do this dumb thing though: Train the lowest level in the party, and when they level up, move up to the next lowest leveled pokémon, if 2 are at the same level, then train the one with lower HP first, if they have the same HP, train the one with lower stats. If all pokémon in party are the same level, my starter must be last in the party because he is "best".
IDK why, but it always worked out for me.

Sonuvaninny.  That's what I do too :O

[Triforce_Luigi]

I always did that up until Emerald. Got Typhlosion and Blastoise up to Level 100 in Crystal and Blue. Destroyed the Elite Four.