The effect itself is simply composed of a mixture of white and yellow stars with transparent trails that move around slowly. They are somewhat similar in appearence to the starstorm slumber/insomnia effects a few years back but slower and with larger stars.

Type: Halloween event

Pairs:
+Other star-based effects
+Orbiting Planets
+Effects based around space (Eg. Nebula)
+Sunbeams (Possibly)

Lots of small, flaming rocks with long, fiery trails zooming around. With meteor the fire is a mixture of reds, oranges and yellows while the comet shower has blues and purples instead

Type: Halloween event

Pairs:
+Starstorm effects
+Orbiting planets
+Nebula

A ring of 1s and 0s that change between 1 and 0 constantly. For binary wall the numbers are green, for firewall they're red, for strange codes they're yellow and for binary coding they are blue.

It is designed to be a lower-tier effect overall, stacking well with other orbiting effects of a similar type (including other effects of this set)

Event: Not event exclusive (Possibly unless we get more MvM stuff)

Pairs:
+Other members of the set
+Galactic/Ancient codex
+Robo crate effects
+Overclock/Memory leak
+Burning flames (Firewall)

Some balloons that fly upwards before vanishing with more spawning in below as they do so. The colours before the names indicate the colours of the balloons that spawn: each having normal, light and dark variants that all spawn.

Another lower-tier effect, though this time with few pairable effects

Pairs:
+Confetti
+Other balloon effects

A small, glowing halo above the player that is slightly larger than the unused one shown on the wiki. Halo of light's halo is a bright yellowish colour while glowing halo features a more blueish tint

Pairs:
+The hat protectors from invasion
+Sunbeams
+Miami nights
+Disco beatdown

A large collection of dark-brown rocks that orbit the player. They are more noticable than, say, nuts'n'bolts but still less than things like bubbling or orbiting planets

This is another low-tier effect designed mainly around the rhyme in its name

Pairs:
+Orbiting planets (Asteroids)
+Space-like effects (Like nebula, for the same reason as above)
+Sunbeams/Sun-based effects ('Sun over a cliff' effect)

A fire-based effect similar to the series 1 scorching and burning flames effects. Spirit flame features a blue outside that fades into a white center while monochrome flame features a black outside that also fades into white.

Event: Halloween event

Pairs:
+Other fire/energy effects
+Ghost effects (Spirit flame)

A group of large, white clouds that slowly orbit the player. Not much else to say really.

Potentially another

Pairs:
+Other cloud-based effects
+Smoking/ Steaming
+Bubbling?
+Sunbeams

Similar to sunbeams, though the individual beams are a bluish white and are much brighter. The area covered by the beams is also slightly reduced, stopping it from being just a slightly recolour.

Pairs:
+Sunbeams (I wonder why)
+"Halo" effects
+Burning/Scorching flames

Multiple small flames that orbit the player, all at slightly different speeds. Endless afterburn's flames are red on the outside and fade into a yellow in the center while eternal afterburn goes from green to white instead.

Event: Halloween event

Pairs:
+Burning/Scorching flames
+Orbiting fire

Multiple rose petals that orbit the player, all slowly decending before despawning while new ones spawn in above (so they don't run out). The colour in the unusual effect names correlate to the colours of the petals, though this is somewhat obvious.

The effect itself can be somewhat hard to see since the petals are small. Though I am not sure if it'd end up as low-tier or a mid-tier effect since the starstorms, while both having double chances, ended up mid tier.

Pairs:
+Moon-based effects (If you want to be dramatic about it)

Lots of bees that orbit and fly around the player. This effect is somewhat comparable to massed flies, though more noticable due to the bee's extra yellow colours.

However, since the effects are still small it could easily end up as another low-tiered effect sadly.

Pairs:
+Massed flies (Obvious)

Lots of stars that appear above the player. They do not move, instead just appearing before disappearing a second later, with more spawning in other places. Starstruck has light yellow stars, star-crossed has light pink and star-dazzled has light blue.

Pairs:
+Moon-based effects
+Starstorm slumber/insomnia
+Other space-based effects (Like orbiting planets)
+Sunbeams

A cloud that sits above the player. It does very little besides a small animation sequence where it changes shape a little. Citrus cloud makes the cloud a light lime colour while english weather makes it a dark grey.

The effect, due to it just being a cloud, would probably only get a low-tier, though citrus runs the chance of mid-tier due to it being noticable due to colour.

Pairs:
+Smoking/ Steaming (Technically)
+Bubbling (Bubble bath again)
+Other cloud effects
+Sunbeams

3 or 4 stars that orbit the player in a coordinated pattern (basically just a ring where they're all the same distance apart). Dizziness makes them a yellowy-gold colour while seeing stars makes them a light grey.

Pairs:
+Other star-based effects (Like the starstorms)
+Other space-based effects (Like orbiting planets)

A small tornado that stays in one place above the player. For tornado the effect is a greyish white while for sandstorm it's more of a light brownish yellow.

Pairs:
+Rubble trouble
+Nuts'n'bolts
+Weather-based effects
+Massed flies (The Swarm!)

Similar to the tornado effects above, though the tornado this time is made of fire, as the name would imply.

Event: Halloween event (probably)

Pairs:
+Other fire effects
+Other tornado effects
+Certain orbiting effects
+Tornado effect partners not mentioned previously

A multitude of different food items that orbit the player. The items include the Sandvich, Dalokohs bar, Buffalo steak sandvich, Bonk!, Crit-o-cola, Mad milk and the Holy mackerel (Though much smaller, slightly transparent versions)

Pairs:
I genuinely don't know for this one...Idk maybe you could pair it with a sammy cap on the heavy?

Groups of clouds that rise up from the player. They start out small before growing larger as they ascend before finally disappearing and another spawning below.

Pairs:
+Other smoke/cloud based effects
+Burning/scorching flames

A bunch of different music notes that orbit the player. Not much else to say really.

Pairs:
Actually have no ideas for what could partner with this one.

A ring above the player that occasionally has spikes and dips appear in it at seemingly random intervals. Heartbeat has a green ring, vibration detector has a red ring, shockwaves has a yellow ring and soundwaves has a blue ring.

Pairs:
+A few of the robocrate effects pair fairly well

Parts of the MvM robots that fall from the sky above the player before vanishing, with more parts spawning in above the player again.

Pairs:
+Some of the MvM effects
+Nuts'n'bolts

Another lot of effects that orbit the player at different heights and at different speeds. Confusion and delay has question marks with colours like team colours, black and grey and question in time has numbers and clocks above the player.

Pairs:
Idk find some ya'self

Fun fact:
-The names are both references to things
--The first one is a Thomas the Tank Engine reference
--The second is a Depeche Mode reference