Brawl/PM hacking is much more easily accessible in most every respect than Sm4sh is. The tools are far simpler, the level of fidelity for modeling/textures is lower but that means less prep work for quality mods. Sm4sh simply hasn't gone very far recently since, outside of a few outlier modders with genuine talent and motivation, Sm4sh hacking is mostly in a similar infancy state as Brawl hacking had: primarily crappy weeaboo and/or "joke" skin mods, 50 bazillion OP moveset hacks, and super-easy texture hacks.
I'd say you'd be fine for the next few years making Brawl/PM hacks.
