Main thing to remember about the Belmonts is that they have just about the worst recoveries in the game, tether nonwithstanding. Using projectiles to gimp is a very safe bet and can lead to kills or SDs, especially if 2nd jump is already burnt. Belmonts can throw a cross boomerang while off stage and still recover, but usually won't use the axe since the end lag often means an SD unless they're fairly high above stage level. You can use that to your advantage by coming in from a high diagonal approach - either to hit him or to force him to use his UpB too soon which will lead to an SD.
Simon and Richter are obviously best at midrange, and I find tend to perform best when on the defensive rather than on offense. If you're Young Link, try hanging back and getting chip damage with projectiles to force him to approach you, then punish any mistakes.