These Pokémon evelve only by trading:

No40 Kadabra > No41 Alakazam
No58 Graveler > No59 Golem
No74 Machoke > No75 Machamp
No76 Clamperl > No77 Huntail/No78 Gorebyss
These Pokémon evolve with stones:
No20 Lombre > No21 Ludicolo (by water stone)(only in Sapphire)
No23 Nuzleaf > No24 Shiftry (by leaf stone)(only in Ruby)
No61 Skitty > No62 Delcatty (by moon stone)
No89 Gloom > No90 Vileplume (by leaf stone)
No89 Gloom > No91 Bellosom (by sun stone)
No153 Vulpix > No154 Ninetales (by fire stone)
No156 Pikachu > No157 Raichu (by thunder stone)
No138 Jigglypuff > 139 Wigglytuff (by moon stone)
Most Pokémon evolve between Lv 34 and Lv 50