Fantastic, thank you very much for the cofnirmation! So I did some message board surfing and found a list of moves that have been used in the overworld at least once, so I just want to make sure I have the complete list (I wanted to plan some overworld move slaves just in case those moves become useable again in future games)
The moves I found are: Cut, Strength, Fly, Surf, Waterfall, Sweet Scent, Dig, Flash, Rock Smash, Teleport, Defog, Dive, Rock Climb, Secret Power, Headbutt, Whirlpool, Milk Drink and Softboiled (Although those last two aren't that important to put on a pokemon) and from what I gather from you, Headbutt, Defog and Whirlpool have no use currently, but Rock Climb (if I remember correctly) can be used in Hoenn (as can Secret Power for the Secret Bases), so five of those moves I may not bother with, but as I said I just want to make sure I have all the overworld moves so I can future proof myself.
Okay, so based on these, I picked 4 overworld move slaves (can't call them HM slaves since they're not all HM moves) but I wanted to group the moves into similar groupings rather than be too random a collection of moves, so if people can suggest alternate groupings or alternate pokemon to get groups of moves that fit in better with each other that would be great!
Lapras: Surf, Waterfall, Whirlpool, Dive (Water travel)
Bibarel: Strength, Dig, Rock Smash, Rock Climb (Caves and obstacles)
Tropius: Fly, Cut, Sweet Scent, Headbutt (No particular theme, outdoors and obstacles maybe?)
Xatu: Flash, Teleport, Defog, Secret Power (Definitely no theme, just whatever left over I guess)