heres what you do
1. go to the lab,BUT RIGHT BEFOR YOU GET ANY POKEMON SAVE!
2.do evreything like go to mr pokemon,ect..... so you can get a few poke balls
3.catch a pokemon or 2.
4. have them hold whatever pokeballs you have left
5.deposit the starter you choose,and 1 more pokemon(both should be holding a poke ball)
6.change boxes but when its in the middle of "SAVING DONT TURN OFF THE POWER" turn it off
7.now you back at professor elms lab when you turn it on again
8.choose a diffrent pokemon
9.go to the cherrygrove pokemon center
10.take the pokemons pokeball you caught eailer that it is holding and give it to the other starter
11.follow step 6 except this time deposit the 1st starter you choose from and the 2nd starter
12.your at the lab yet again and this time choose the last starer(note: this is the starter where you opponet chooeses you weakness)
13.for good measure save
so their it is,you get 2 pokeballs befor you can buy them and the 3 startes.