This is something you should be mentioning when you post the combo.
Although I'm not the meta's creator, I'm going to make a statement here in regards to a lot of the combos that have been posted. In general, the boost that a combo creates should be inversely proportional to the viability of the moves that are in it. A combo that requires two terrible moves (like Astonish + Scary Face) should be pretty powerful to compensate for the fact that you have to waste half of your moveslots to do it. A combo that consists of two viable moves (like Earthquake + Icicle Crash) should have very little boosts if any at all. If two particular moves are viable options on the same set for several viable Pokemon (like Dragon Dance + Dragon Claw), there most definitely shouldn't be a boost.
Even with the above, we need to be reasonable with our boosts. Sure, nobody uses Charge, but giving Hyper Beam 195 Base Power without recharge, STAB with 90% of the Mons who get it, and a 30% Paralysis chance is just ridiculous. Some examples that I think are pretty good are zerobreaker's Gyro Ball + Rapid Spin and Valzy's Electroweb + Sticky Web.
tl;dr: This may be a Pet Mod, but it's still a metagame, and metagames need to be balanced.
Also, more combos:
- Spiky Shield + Spikes (Spike Ejection): Lays two layers of Spikes instead of one.
- Vine Whip/Power Whip + Bind (Lasso): Bind becomes Grass-type, is guaranteed to hit, and lasts five turns.
- Camouflage + Priority move (Sneak Attack): The opponent is guaranteed to flinch this turn.
- Lock-On + Multi-hitting move (Target Strike): The multi-hitting move is guaranteed to crit and hit 5 times if it can.
- Grassy Terrain + Grass Whistle (Fresh Grass Whistle): Grass Whistle always works for the duration of Grassy Terrain.