yay special moves time!
:3p:(mantis)
press :p: repeatdly - its use is more or less to push away more than anything.
:dp:+:k: - anti air and not too bad but its no dragonpunch can press kick afterwards for additional kicks. and also the main move used in in gens custom combo.
supers
:qcf::qcf:+:p: - gen runs through the opponent and does multiple hits not safe to do outside of combo or unless you opponent is recovering and your in the correct distance. in most cases level 2 is the best for this super.
also if you land a level 2 in the corner you can switch into crane and do a level 1 anti air super and it will connect! inigma is a player on ggpo who often does this.
:qcb::qcb:+:p: - touch of death! if this move connects a timer goes down and does damage over time if it reaches zero your opponent gets knocked down and dizzy. but if they hit you timer dissapears. the damage over time increases with level.
:3k:(crane)
:l: then :r: + :p: - a roll that hits that ends in a stab punch the lp version is safe and fast and quite repeatable. hp and mp versions go further and gen rolls more
also with the move being a roll it carries some similar properties it can go under fireballs if timed but also its possible for people to throw you out of this move! but even the during the roll it hits the opponent so that unlikely to happen often.
:d: then :u: or :ub: or :uf: + :k: - gens off the wall dive move this is probably the most complicated off the wall dive move in street fighter ever but with that complexity comes alot of control over what your dive can do.
assuming you are standing on the left side facing your opponent on the right.
doing the move normally will make you jump to the left wall and then jump off it and kick your opponent very similar to adons jaguar tooth.
however if you tap :l: the second before touching the wall you will cancel the jump kick and just land near the edge of the screen.
if you tap :r: instead you will also do a jump kick but this version reaches alot further and has nearly the range of the full screen.
if you do :d: then :uf: instead gen will jump to the opposite wall on the right side then do his dive kick you can also modify the move and cancel it like if you were normally doing it.
now gen also has another version of off the wall except its off the ceiling. so the command is
:d: then :u:,:u: tapping up twice also works for me most of the time 
so what will happen is after gen jumps onto the side wall he will then jump onto of the ceiling and then do a headstomp downwards like dictator
leaving the joystick neutral or taping down will also do the headstomp
also what you can do once you reach the ceiling is tap :u: again for a third time and he will cancel the head stomp or press :db: or :df: to do a angled dive kick that hits to the right or left . this is used if your oponent moves once you hit the ceiling.
the angled dive kick is also good for when your opponent is in the corner and in mid air.
supers
:qcf::qcf: + :k: gens anti air super depending on level it will travel farther. like zangeifs anti air super it is sorta crap against some jump ins like downward splash moves.
it can be comboed from c.:lk: launcher
:qcb::qcb: +:k: (while jumping) super dive kick this works very much like gens off the wall kick except he firstly dosnt need to jump off a wall for the first hit and secondly distance and wall direction control is done by button presses not directions on the stick. at its most basic the useage is quite like akumas air fireball super.
the higher the level super you do the more additional kicks gen will do. with level 1 doing one kick and then the off the wall kick. during all the hits after the first you can do the following. this is assuming you are doing the move from the left side.
pressing :mk: gen will do headstomp
pressing :lk: gen will jump to the left wall and do a second jump kick off the left wall
after pressing :lk: to jump onto the left wall again pressing :hk: will make gen do an extremely flat angled fly kick that reaches the distance of the whole screen.
while pressing :hk: and then :lk: will do the same but off the right wall