No. He did not appear in Season 12.
None, that I recall.
The 1st fight: "DaBoom" (Season 2).The 2nd fight: "Blind Ambition" (Season 4).The 3rd fight: "No Chris Left Behind" (Season 5).Ernie's 4th : Cameo in "Meet The Quagmires"(Season 5) but a fight is prevented.Ernie's 5th : Cameo in "The Juice is Loose"(Season 7) in the mob confronting O.J. SimpsonErnie's 6th : Cameo in "Big Man on Hippocampus"(Season 8) He hits Peter with an odd number of objects helping him to regain his memory.Ernie's 7th : Cameo in "Go Stewie Go" (Season 8)Ernie's 8th & 10th : Ernie played the role of Boba Fett in "Something Something Something Dark Side"(Season 8) & "It's a Trap" (Season 9)Ernie's 9th : Cameo in "Trading Spaces" (Season 9)Ernie's 11th : The fourth Peter vs Ernie fighthappened in the Season 10 finale, "Internal Affairs"Ernie's 12th appearance and fifth fight was seen in reverse, in Season 11's "Yug Ylimaf"
Season 8 | Episode 8: Dog Gone
Mind over Murder
Meet the Quagmires is episode 18 of season 5 of Family Guy.
The sixth season.
Bert and Ernie
A Very Special Family Guy Freakin' Christmas was in Season Three.Road to the North Pole was in Season Nine.
Season Seven
season 7
Season 6
No, David Hyde Pierce didn't appear on Family Guy. He did appear on The Simpsons as Cecil Terwilliger. He also appeared on Osmosis Jones.