ivysaur is the hardest character to learn, he comes sort of naturally to me though so lol. nair is the best move ever, it chains into itself, it sets opponents up perfectly for an uair, it ***** shields, etc. abuse it.
back air is godly too, it doesnt do much percent though so use it a couple of times, your opponent will probably airdodge after the first or second one, so learn when they will airdodge and punish the airdodge
ftilt is awesome too it does a lot of damage and has a bunch of priority
alot of my ivysaur game is getting people to fall for my upsmash honestly XD i'm pretty good at it. it ***** dodges.
for squirtle all you have to do is attack the corner of their shield with full jump bairs or fairs over and over again. or stay back and go for the hydroplaned grab. save your dthrow for when your opponent has enough % to be killed with it. you should be using your fthrow at medium percentages and uthrow at low percentages otherwise. you should hydroplane any other move except for the forward hydroplane usmash at appropriate times. at low percentages try to land an utilt and chain it with more utilts, then chain into uairs when you see your opponent getting out.
thats all i can think of right now :3