Here is the list of All time Greats that Federer managed to beat in Slam Finals:
Winner 2003 Wimbledon (1) Grass
Mark Philippoussis 7–6(7–5), 6–2, 7–6(7–3)
Winner 2004 Australian Open (1)
Hard Marat Safin 7–6(7–3), 6–4, 6–2
Winner 2004 Wimbledon (2) Grass
Andy Roddick 4–6, 7–5, 7–6(7–3), 6–4
Winner 2004 US Open (1) Hard
Lleyton Hewitt 6–0, 7–6(7–3), 6–0
Winner 2005 Wimbledon (3) Grass
Andy Roddick 6–2, 7–6(7–2), 6–4
Winner 2005 US Open (2) Hard
Andre Agassi 6–3, 2–6, 7–6(7–1), 6–1
Winner 2006 Australian Open (2) Hard
Marcos Baghdatis 5–7, 7–5, 6–0, 6–2
Winner 2006 Wimbledon (4) Grass
Rafael Nadal 6–0, 7–6(7–5), 6–7(2–7), 6–3
Winner 2006 US Open (3) Hard
Andy Roddick 6–2, 4–6, 7–5, 6–1
Winner 2007 Australian Open (3) Hard
Fernando González 7–6(7–2), 6–4, 6–4
Winner 2007 Wimbledon (5) Grass
Rafael Nadal 7–6(9–7), 4–6, 7–6(7–3), 2–6, 6–2
Winner 2007 US Open (4) Hard
Novak Djokovic 7–6(7–4), 7–6(7–2), 6–4
Winner 2008 US Open (5) Hard
Andy Murray 6–2, 7–5, 6–2
Winner 2009 French Open (1) Clay
Robin Söderling 6–1, 7–6(7–1), 6–4
Winner 2009 Wimbledon (6) Grass
Andy Roddick 5–7, 7–6(8–6), 7–6(7–5), 3–6, 16–14
Winner 2010 Australian Open (4) Hard
Andy Murray 6–3, 6–4, 7–6(13–11)
The only time he defeated Nadal & Djoker was when they were really during the formative years. Talk about standing up against your opponents when they start to fight back.
Fed basically could not even fight back Nadal at the peak of his physical abilities which was 2008 when he was 26 years old(exactly same age as Rafa is now and 1 year older than Djoker is). if you ask Fed fans, they would say Nadal was in Prime@ 2008 (when he was just 22 years) and Fed was getting older
GOAT, yeah very well, if his worshipers think so!