I have played PS 2 for 64 a long time ago so I'm pulling this all from memory. Its been like 10 years since I've played it lol
I'm not 100% sure if this is what I did but I believe that I traded/bred pokemon in one of my Gameboy games (Silver Version I think it was) to get the babies to meet the lvl 5 requirement and then spent a bunch of money on TMs if the baby pokemon didn't have the moves I wanted. I know one of the pokemon I used was Pichu.
I then attached that game to my 64 and registered my lvl 5 pokemon onto my PS 2 so I could use them.
I don't have a certain team that I like. I prefer to use pokemon that are my favorites unless they don't meet the type match ups that I need. I normally try to have at least 1 grass, fire, and water types or pokemon that can use those type of abilities