You can't really make G&W approach you since he can just camp back with D-tilt and N-air and none of your attacks will be able to touch him. You have to bait him to approach, shield it, and then grab him.
True enough your grab can hit him out of his D-tilt, but he's not going to be using it and just sit there waiting for you to grab him. It has virtually zero ending lag btw.
If you tech the D-throw, G&W will usually kill you with F-air, and it's almost as deadly as his Smashes when undiminished. He can set it up pretty well in aerial combat or offstage.
I've not really played any Olimars that pivot grab a lot, so I want to challenge one who thinks they know the G&W vs Olimar matchup well.
I find corneria to be a strong counterpick against peach, and it seems to be legal alot more at tournaments than banned. Standing near the top of the wing makes it difficult for peach to approach at you from the air seeing as how she travels horizontally, and while standing on the slant, the pikmin you throw with latch go diagonally down the wing. Also, corneria has a large increase in yellows, which are helpful in out prioritizing peach's aerials. However NEVER go to the right section of corneria against peach... it's far too easy for peach to combo olimar with the wall there, and not the other way around, like against other characters (pikachu lol)