Godzilla

Rodan got his solo film in 1955, and was a major player in Showa, but afterwards, he got 1 appearance in Heisei and wasn't even the main focus of that movie, and then was in Final Wars, and then was in KotM. even Michael Dougherty admitted he was always more of a side kick. meanwhile Mothra got her solo movie, a movie vs Godzilla in Showa, and was a major player afterwards, then appeared as the main focus again in a Heisei film, not to mention the Rebirth of Mothra trilogy, and then appeared in 3 Millennium movies. and then of course she was in KotM. meanwhile Anguirus was in only 4 Showa movies (Raids Again, Destroy All Monsters, vs Gigan and vs Mechagodzilla), and wouldn't appear again until Final Wars. and then all he got was his blink and you'll miss it skeleton in KotM. he was then in Singular Point after being absent for 17 years. and then of course there's Varan who hasn't appeared since a blink and you'll miss it cameo in Destroy all Monsters.