After you get the National Pokédex, you get access to a wide variety of areas. In these areas you will battle trainers with Pokémon from regions other than Sinnoh, most of whom are actually wild. Below is a partial list of these Pokémon and most of them are wild, and if they themselves aren't, then chances are their pre-evos are somewhere to be found, so be on the look out:

Nat. No.	Selection Pic	Name	Type 1	Type 2
#019		Rattata
#020		Raticate
#021		Spearow
#022		Fearow
#028		Sandslash
#043		Oddish
#044		Gloom
#052		Meowth
#053		Persian
#056		Mankey
#059		Arcanine
#061		Poliwhirl
#069		Bellsprout
#070		Weepinbell
#079		Slowpoke
#080		Slowbro
#083		Farfetch'd
#085		Dodrio
#086		Seel
#097		Hypno
#102		Exeggcute
#105		Marowak
#108		Lickitung
#110		Weezing
#115		Kangaskhan
#117		Seadra
#123		Scyther
#127		Pinsir
#128		Tauros
#131		Lapras
#147		Dratini
#148		Dragonair
#178		Xatu
#180		Flaaffy
#193		Yanma
#206		Dunsparce
#217		Ursaring
#219		Magcargo
#228		Houndour
#232		Donphan
#236		Tyrogue
#241		Miltank
#263		Zigzagoon
#277		Swellow
#281		Kirlia
#286		Breloom
#288		Vigoroth
#294		Loudred
#296		Makuhita
#297		Hariyama
#301		Delcatty
#318		Carvanha
#319		Sharpedo
#323		Camerupt
#328		Trapinch
#329		Vibrava
#332		Cacturne
#333		Swablu
#334		Altaria
#342		Crawdaunt
#344		Claydol
#353		Shuppet
#355		Duskull
#356		Dusclops
#357		Tropius
#364		Sealeo
#370		Luvdisc
#373		Salamence
#376		Metagross