Your Blaziken moveset is good. However, an Adamant personality would work better. Rock Slide is a another choice instead of Overheat, but either move will work fine. Put 252 EVs each in Attack and Speed, and put the other 6 into HP.
If you want more of a standard sweeper instead of an Endure/Reversal Blaziken, you could use moves like this:
Bulk Up/Swords Dance
Earthquake
Brick Break
Rock Slide/HP Rock/Focus Punch/Overheat
@Salac Berry.
Once again, Adamant personality, with the same EVs that I mentioned in the above moveset would work great.
Gyarados-With Dragon Dance, you won't really need Thunder Wave, as Dragon Dance will provide you with speed. Dragon Dance and Earthquake are great. Taunt is also a popular choice, as it provides protection from hazing/pseudohazing. As for the last move, something like Body Slam, Double-Edge, or Hidden Power Flying would be good, although trying to get a decent type/power Hidden Power in-game is rather diffcult. Adamant personality is best, with EVS of 252 each for Speed and Attack, and the other 6 in Special Defense.