Beat 1P Challenge Mode in Hard Mode, with ALL vents used and try not to fall onto the ground often. Make sure that you already got Ouja first.

Destwilder: Beat 1P Battle Mode with Kamen Rider Tiger
Gigazelle: Beat 1P Battle Mode with Kamen Rider Impaler
Kamen Rider Femme: Beat 1P Battle Mode with Kamen Rider Ryuki
Kamen Rider Impaler: Beat 1P Battle Mode with Kamen Rider Zolda
Kamen Rider Knight Survive: Collect all 64 cards in Card Get Mode
Kamen Rider Odin: Beat 1P Battle Mode with Kamen Rider Femme
Kamen Rider Ouja: Beat 1P Challenge Mode once
Kamen Rider Ouja (Gai deck): Beat 1P Battle Mode with Kamen Rider Ouja
Kamen Rider Ouja (Genocider): Beat 1P Battle Mode with Kamen Rider Ouja (Raia deck)
Kamen Rider Ouja (Raia deck): Beat 1P Battle Mode with Kamen Rider Ouja (Gai deck)
Kamen Rider Ryuga: Beat 1P Battle Mode with all characters
Kamen Rider Ryuki (Blank Form): Beat 1P Challenge Mode twice
Kamen Rider Ryuki Survive: Beat 1P Battle Mode with Kamen Rider Knight Survive
Kamen Rider Tiger: Beat 1P Battle Mode with Kamen Rider Knight
Kamen Rider Verde: Beat 1P Battle Mode with Kamen Rider Raia
Megazelle: Beat 1P Battle Mode with Gigazelle
Metalgelas: Beat 1P Battle Mode with Kamen Rider Gai
Volcancer: Beat 1P Battle Mode with Kamen Rider Scissors
Zebraskull Bronze: Find the Zebraskull Bronze card in Card Get Mode
Zebraskull Iron: Find the Zebraskull Iron card in Card Get Mode