Cheap tactics
--------------
CHAINGRABS, fox and falco nd falcon become alot easier if u can master chaingrab -> uairs -> F/Dsmash (wait for them to DI forwards).
Fall off the edge, drop down about the height of your 2nd jump and perform a jumping neutral A - test this in friendles first, cos if u mess up your dead. Gimps spacies -> B really well. If they clock onto this and start doing fire fox/bird, the chances are itll be rushed and poorly aimed - while doing the neutral A, move back onto the stage, cancel and cape. Nair trades with falco's and marths upB's, or beats them im not sure
Also if thats proving too suicidal, fireball to intercept recoverie is good, because they almost always do a hasty fire fox/bird - easy cape. Be wary of teching the cape though, they may recover str8 away so be ready.
Most foxes and falcos think theyr being sneaky when they do the fire directly up - use ur mindgames to tell when they are gnna do this - its obvious. normally after failing to trick you the first time however they are most likely gnna try and sweetspot the edge. its safe if the fox/falco is within first jump range, to jump down and just time the cape so they get caped regardless.
For caping marth, (its better to use neutral A though imo) you need to face away from the edge, backflip over and cape towards the stage. If this misses neutral A/ reverse bair back onto the stage to be safe. If your levels u might be able to waveland the bair, lol..
Normal tactics
---------------
Umm this is by no means my specialty, i am training to be a master gimper.
Fox/Falco - 100%, Fair -> Fsmash, free kill no arguments lol.
Falcon - 70-80%, Fair -> Fsmash, free kill no arguments lol. Shiek somewhere too
Marth - 40-50%, Fair -> Fsmash, free kill no arguments lol.
you can charge all of the smashes up, unless they DI the fair very well its a kill.
At around 15% Marth, 50% fox and falco they cant get outta utilt juggle without DI for a fair few hits. Rember u can substitute another utilt for a grab., esp do this when they begin to di forward, cos a forward di'd down throw goes nicely to uair -> jab
If you can grab the edge, and catch marth with a bair while he does his jump (while recovering) there is no way back for him, he is definatly dead. He may neutral A as he jumps - u may need to anticipate this, fake falling from the edge, grab it again, then bair/nair
When your opp gets to a silly % and your finding it hard to kill, dthrow -> nair should finish them off.
If at the edge of the stage, and the (heavy) opponent is closer to the edge, facing away, dtilt has a use at 100% - it makes them trip, they'll probably go to tech behind you if theres not enough space behind them (hence at the edge of the stage) - anticipate this with an Fsmash if possible.
Spam utilts as a defensive maneuver, it beats the knee most times, and ive seen it beat falcos dair. Also remember that the the frames Usmash hits on also makes marios head invincible - this is useful as hell. Uair also has deceivingly high priority, more then neutral A i think. may even be disjointed, my friend maintains he has never been able to hit my legs during the animation.
Be wary of falcon and peach.
This is all pretty basic stuff so u probably know most of it, but ehh i just want to help people out. Have a good time, hope you do well!
