well first thing first, you can find the download link to pokesav and links to .pkm files (the pokemon themselfs) and events pokemon at this site's homepage, now as for your questions, the pokesav itself dosnt have anything to do with Wi-Fi with your DS but if you whant to get the pokemon you whant there are 3 options: by code (AR required), trade (Wi-Fi connection required) and edit your .sav file (with a flash card, if you can do it by another way i do not know how), pokesav can change your items, poketch, poffins, seals, record, underground items and a few other things, basicly pokesav can change anything basic you have in your game (not makeing non-exist pokemon like ??? arceus), if you have any questions you can pm me anytime