You know airdodging loses to doing nothing right? If your opponent is consistently airdodging your followups, then you need to be patient, wait for the airdodge, and then attack.
Sonic is an extremely obnoxious matchup for anyone, but especially for characters like Kirby. Ideally you'd get him above you and then juggle him, but thanks to his Spring he can jump way out of reach, and then attempt to land and reset the situation. Of course, on the ground he can also just run away really fast to reset the situation. Your best bet is probably empty shorthops/walking towards him if you have to approach. Jab stops his SideB approach, and then if you jab afterwards you'll at least clank with his own jab followup. It's going to be one of those boring matchups, where you can't combo him very well (you can get some 2-3 hit combos, but anytime he gets above you from uptilts or whatever he Springs away) and it requires a lot of patience. And reaction time. Which is impossible on wifi.