I compiled a list once. This changes over time of course. You won't be able to expect to write a list once and then not update it as new things show up on CPAN or as perl changes.
# A dictionary of stuff that can show up in UNIVERSAL.
our @UNIVERSAL_METHODS = (
# core perl
qw( isa can VERSION ),
# core perl 5.9.4+
'DOES',
# UNIVERSAL.pm
'import',
# UNIVERSAL/require.pm
qw( require use ),
# UNIVERSAL/dump.pm
qw( blessed dump peek refaddr ),
# UNIVERSAL/exports.pm
'exports',
# UNIVERSAL/moniker.pm
qw( moniker plural_moniker ),
# UNIVERSAL/which.pm
'which',
# SUPER.pm
qw( super SUPER ),
);