Quick, who had a Top Forty hit covering a Who song? Nope, not Tina Turner; a studio group from Philadelphia called the Assembled Multitude went to Number Sixteen in 1970 with "Overture from Tommy (A Rock Opera)." Tom Sellers, the mastermind behind the group, was only 21 or so (his biographical data is hard to come by) at the time he was arranging instrumental versions of not just his only hit but the Beatles' "I Want You (She's So Heavy)" and "Ohio." I'm probably forgetting something, but that may be the only Who cover to reach the Top Forty. (Limp Bizkit's cover of "Behind Blue Eyes" reached Number Twenty-Four on the Billboard Top 40 Mainstream in 2004, which you can count if you want.)
Now, who had a hit with a cover of a Sly and the Family Stone song? Here's where we turn to Ike and Tina, who went to Number Thirty-Four in August 1970 with their version of "I Want to Take You Higher," credited actually to Ike & Tina Turner & the Ikettes. Sly's original was on the charts for three weeks in early spring of 1970, two months before Ike and Tina crashed the party.
There may be other Sly Stone covers in the Top Forty, but I can't think of them right now. I've been really busy lately.