Stuff you can do to deal with lasers:
Most importantly, get down wavedash OOS. Make sure you do it cleanly and quickly, this allows you to use Ike's strong ground movement to weave between Falco's laser game. Falco's ground movement is subpar, so it's something he struggles with if you can get the upper hand and push him to a corner where he can only shoot close range lasers. Retreat wd oos -> whiff punish is great if a Falco goes in after a laser and does something unsafe.
Learn to powershield consistently (it's a lot easier if you map it to a non-analog button like X/Y but can be done fine with the triggers), it doesn't stop Falco's laser game entirely but it makes him respect your options more at mid-close range and can alleviate some pressure from long range. You don't always have to go for PS laser -> grab/combo, sometimes all you can do is PS laser -> get better positioning, and that's fine.
Falco's lasers have start-up, bear in mind that you can hit him before he even shoots if he shoots point blank.
Most important thing to keep in mind imo: Don't get hit by lasers and panic, keep your cool. A lot of people will start jumping when Falco pressures with lasers, most of Ike's aerial options are slow/easy to stuff out so jumping when Falco does this will put you in a bad position. Also keep in mind that laser -> approach isn't a true combo and you can stuff out bad approaches with ground moves, so if a Falco is approaching recklessly after lasers you can combat that.
