Rel sucks period. Pound should only be used in three scenarios, PARTICULARLY against yoshi:
1. Punishing
2. Recovery
3. Outprioritizing an approach.
You use pound as offense in two and only two scenarios against yoshi, he is back airing at you and you use pound as a priority bully, or he is going in for an obvious up smash. Any other pound you hit with is simply luck or they have made a mistake, which would mean you used it to punish them. Your best approaches are running shield and airdodge approaches. Don't be afraid to DACUS him when hes tossing an egg. If you find that an egg is going to hit you, try to shield it and then Fair OoS. I'm really good at predicting yoshi's recovery pattern because I used to main him, so that's another reason i **** yoshies so hard. It's a tough matchup to learn and unfortunately not an important one =/