The following are the most suggested Oracle Certifications for Oracle Application Developers in Forms and Reports and as you already know that Oracle Forms 12c also released, so it is going to be used in long run.
Oracle Certified Professional, Oracle Fusion Middleware 11g Forms Developer
The Oracle Fusion Middleware (FMW) 11g Forms Developer certification is designed for individuals who possess a strong foundation in SQL and PL/SQL basics and wish to learn to use Oracle Forms Builder 11g to rapidly build scalable, high-performance applications for the Web. This certification covers topics such as: designing code for reuse, using GUI controls and writing triggers, troubleshooting applications and using WebUtil to interact with client computers.
Oracle Forms Developer Certified Professional
This certification is only available as an upgrade from Oracle Application Developer Rel. 1 OCP. We strongly recommend that you continue on your upgrade path to the current Oracle Forms Developer Certified Professional
Oracle Internet Application Developer Certified Professional, Oracle Forms Developer Release 6/6i
Oracle offers a complete, integrated set of application development tools that support any development approach, technology platform, or operating system. Oracle PL/SQL Developer Certified Associates demonstrate expertise in building database-centric Internet applications for both Oracle9i and Oracle Database 10g. Oracle Forms Developer Certified Professionals gain greater credibility, a higher level of efficiency, and improved job performance as application developers.