Bubble is a move that shoots enemy's and stuns them for 1 second. It is good if you wanna escape a legendary (not very good to get away from deoxys.) It is in-between short and long range.
Tackle is a move that makes you simply charge forwards in hopes of hitting a pokemon. It isn't a very strong move.
Watergun is a move that like bubble shoots the enemy however it does not stun them and it is much faster. It is also long-range.
Squirtle evolves into Wortortle