hey some quick things to incorporate into your style bigman:
1- when you get right behind your opponent and their back is facing you shield and
wait for their spotdodge then its a free grab everytime. if they dont spotdodge they are either going to shield or run away. if you get hit by an attack that means either you forgot to put up your shield or you chose to get behind them at the wrong moment. and also watch out for OOS shiz if your opponent does shield and you havent grabbed in time
2- when ddd is in the air and u know hes going to be offensive you want to get right under them. they are either going to do 1 of three things(bair/inhale/airdodge into ground>grab/utilt) read your opponent and pshield the bair>grab or force an inhale and punish with something or dsmash if you dont think you can punish their airdodge into ground
3- never tjolt a ddd near the edge and DI towards them. its a free grab for d3 everytime. DI away and off the stage and use your amazing recovery to prevent any damage you may sustain from getting grabbed.
4- when grabbing the edge, if you want to use a quick move do not dair unless they are on the stage. just hit away and use your nair. its much faster and more knockback. plus it leaves you below the edge and gives you plenty of room for a safe recovery.
Edit:
Watched the rest of you videos and noticed a lot-
1- you never crossover your opponent(land behind them). learn to airdodge behind and different ways to get behind the opponent. watch some of esams vids. he does it a lot.
2- the snake didnt know how to shield tjolts. you should have recognized this and tjolted the entire time and run away. when you tried being aggro you were really predictable and easily punished. the snake wasnt too good at handling his nades either. that is totally your advantage. learn how to run up at the snake an p-shield his ftilt then spotdodge his second attempt(if he does it). everytime snake ftilts he moves towards the direction of the ftilt and its easy grabbing from there. snake is wrecked hard once you can grab him. up close the snake never predicted your shield and never grabbed you when you had a nade in your possesion or when a mortar was falling overhead. and i doubt he would have been able to grab you if you were shielding in front of him(baiting anything of course).
3- use different throws once your opponent is at high percents and pummel more. your fthrow was staled a lot and you forget about dthrow and bthrow and uthrow which would have put you in a better position and them at higher percents.
Edit 2:
1- I just realized another thing!!!! i never see you use your jab. you need to experiment with it and incorporate it.
2- a real nice spacing tool is dtilt>fsmash too. you'd be surprised how many times it works.
AND ANOTHER THING:
i dont see you reading your opponent. i just see you using pika and not reacting to your opponent. you need to start watching your opponent more intently and predict where they are going to land after being in the air or when they are going to shield or spotdodge, etc... i do see a lot of good stuff from you. but it could be better