I Got Pokemon Diamond

[The name master]

I finally got enough money to buy Pokemon Diamond.

So far, I got Piplup and Starly. I want a Pachirisu, but I don't know where to find one (don't tell me though!) I keep finding Shinx instead! I'm thinking of getting a Leafeon and a fire type.

[Petzbreeder]

I want a Pachirisu
I keep finding Shinx instead!

If you're searching where I think you are, you need to play through the story a little more to reach where Pachirisu is.

[The name master]

I just beat my rival for the first time (not dawn but the other guy) does hat give you a clue?

Why is Chimchar the only fire types in gen 4? >_<

[Petzbreeder]

Not revealing exactly where, but Pachirisu is available after the first gym somewhere.
To be honest, even though I looked it up earlier today, I've forgotten where to find Pachirisu myself!

Chimchar and evolutions aren't the only fire types in Sinnoh. You can get Magmortar and Heatran as well.

[The name master]

Heatran is a legendary that I probably can't get legit and magmortor I have to get by evolving Magmar through a trade or something, which I can't do because I don't have another copy of the game! And I don't think Magmar is even obtainable in gen 4!

[Petzbreeder]

Heatran is found in Stark Mountain. I don't think an event is required to access it.

[The Hooded Trainer]

No event, but equally thats post game stuff, so not really all that helpful.

[The name master]

Eevee isn't available until I beat the game! Not fair! I want a Leafeon!

[Inferna]

Ponyta is the only other fire type available in Diamond that's accessible during the game iirc.
From what I remember you can probably play through without a fire type, Gardenia and the steel gym leader (name escapes me) would be easy enough with a flying and ground type respectively. I'm sure Lucario and maybe Toxicroak learn fire type moves??

[Petzbreeder]

the steel gym leader (name escapes me)

You mean Byron?

[The Hooded Trainer]

Yeah, I dont remember ever using fire types in gen 4. Candice (the ice leader, shockingly) should be easy enough too, especially if you go the extra mile and get lucario.

[The name master]

Candice (the ice leader, shockingly)

Is it shocking like gen 2 bug gym leader? (Metapod, Kakuna and Scyther if I remember correctly)

if you go the extra mile and get lucario.

I'd like a Lucario, but forget it if I have to legit raise it from level 1(?) at a late point of the game(?)

[The Hooded Trainer]

Ehh, you do, but it surprisingly doesnt take that long with the exp share.