user bearsfan092 has some great rng abuse tutorials on youtube, they've really helped, and the procedures are similar to the onsite guides so you can refer to them while you do the RNG process.
There are previous gen cloning codes on the pc, but I don't suggest using the DPPT ones, rather the HGSS ones seem more stable in my opinion, the Platinum ones gave me bad eggs (I've used a flashcart with built in AR ,I'm stating this from experience).
I'd suggest using a DS Lite as it was the first handheld supported by the RNG reporter, and I believe it would be easier for you, and you can also make use of alternating delay with the dual slot feature since you have gen 3 retail cartridges (although you can just change the year to alter the delay as I've read there are inconsistencies with using the dual slot).
IIRC, You need to have pokegen and a flashcart/ a way of backing up your retail save file (See NDS backup tool) to inject wondercards. Projectpokemon has the wondercards if you're wondering too, and also I recommend that if you plan on trading injected wondercards that you state that they are obtained through that method, and also include all codes (if you plan on offering those pokemon in a trade thread).
I can't PM you now tho, so maybe you're better off finding others to help you on conversation. Good luck.
edit: With the removal of wifi, cloning via fakegts is no longer supported, you're better off learning using .pkm files if you want to go to that route and also you should familiarize yourself with pokegen as it supports .pkm files, so you can clone the pokemon from there.