It is according to your source architecture.
You said it is Solaris, but is it Solaris Sparc or Solaris intel?
Anyways, I suppose it is Solaris Sparc. So it is a big endian.
As for the application tier migration , there is only one document to follow ..
Here -> Application Tier Platform Migration with Oracle E-Business Suite Release 12 (Doc ID 438086.1)
Basically, what you need to is to, copy the necessary file, Install the Application Tier Technology Stack and configure.
As for the Db migration, it highly depends on your architecture and the method that you feel yourself comfortable..
These kinds of cross platform migration can be done using expdp-impdp, or transportable tablespaces.
As you may guess , you will use logical migration methods..
Note that, using Goldengate for EBS migration is not supported..
So what I recommend for your is, "analyze expdp-impdp & transportable tablespaces methods".
Analyze term in terms of downtime as well..
According to your analysis, choose your migration method.
Here are some useful documents for you:
EBS R12 - Using Transportable Tablespaces for EBS Release 12 Using Database 11gR2 [1311487.1]
Export/import process for 12.0 or 12.1 using 11gr1 or 11gr2(Doc ID 741818.1)
EBS 11i - Using Transportable Tablespaces to Migrate Oracle E-Business Suite Release 11i Using Oracle Database 11g Release 2 Enterprise Edition [1366265.1]
Also read this post it is for 11i and HPUX but it will give you some clues and general information about the process ->
https://ermanarslan.blogspot.com/2015/02/exadata-ebs-11i-exadata-migration-from.html